diff --git a/.gitignore b/.gitignore
index 65bb4418..43ab9c0a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -14,5 +14,6 @@
 /third_party/gyp/gyp
 /third_party/llvm
 /third_party/mini_chromium/mini_chromium
+/third_party/zlib/zlib
 /xcodebuild
 tags
diff --git a/DEPS b/DEPS
index 0da988b7..4aa8dd5a 100644
--- a/DEPS
+++ b/DEPS
@@ -39,6 +39,9 @@ deps = {
   'crashpad/third_party/mini_chromium/mini_chromium':
       Var('chromium_git') + '/chromium/mini_chromium@' +
       'f65519e442d23498937251e680a3b113927613b0',
+  'crashpad/third_party/zlib/zlib':
+      Var('chromium_git') + '/chromium/src/third_party/zlib@' +
+      '13dc246a58e4b72104d35f9b1809af95221ebda7',
 }
 
 hooks = [
diff --git a/build/crashpad_dependencies.gypi b/build/crashpad_dependencies.gypi
index 417d462b..7fd1cf66 100644
--- a/build/crashpad_dependencies.gypi
+++ b/build/crashpad_dependencies.gypi
@@ -13,16 +13,12 @@
 # limitations under the License.
 
 {
-  # Crashpad can obtain dependencies in three different ways, directed by the
-  # crashpad_standalone GYP variable. It may have these values:
+  # Crashpad’s GYP build can obtain dependencies in two different ways, directed
+  # by the crashpad_standalone GYP variable. It may have these values:
   #   standalone
   #     A “standalone” Crashpad build, where the dependencies are in the
   #     Crashpad tree. third_party/mini_chromium and third_party/gtest provide
   #     the base and gtest libraries.
-  #   chromium
-  #     An in-Chromium build, where Crashpad is within the Chromium tree.
-  #     Chromium provides its own base library and its copy of the gtest
-  #     library.
   #   external
   #     A build with external dependencies. mini_chromium provides the base
   #     library, but it’s located outside of the Crashpad tree, as is gtest.
@@ -30,13 +26,15 @@
   # In order for Crashpad’s .gyp files to reference the correct versions
   # depending on how dependencies are being provided, include this .gypi file
   # and reference the crashpad_dependencies variable.
+  #
+  # Note that Crashpad’s in-Chromium build uses GN instead of GYP, and
+  # Chromium’s GN build configures Crashpad to use Chromium’s own base library
+  # and its copy of the gtest library.
 
   'variables': {
-    # When building as a standalone project or with external dependencies,
-    # build/gyp_crashpad.py sets crashpad_dependencies to "standalone" or
-    # "external", and this % assignment will not override it. The variable will
-    # not be set by anything else when building as part of Chromium, so in that
-    # case, this will define it with value "chromium".
-    'crashpad_dependencies%': 'chromium',
+    # When with external dependencies, build/gyp_crashpad.py sets
+    # crashpad_dependencies to "external", and this % assignment will not
+    # override it.
+    'crashpad_dependencies%': 'standalone',
   },
 }
diff --git a/build/gyp_crashpad.py b/build/gyp_crashpad.py
index 741c8126..fe9da840 100755
--- a/build/gyp_crashpad.py
+++ b/build/gyp_crashpad.py
@@ -31,12 +31,12 @@ def ChooseDependencyPath(local_path, external_path):
     external_path: The external path to fall back to.
 
   Returns:
-    A 2-tuple. The first element is 'standalone' or 'external', depending on
-    whether local_path or external_path was chosen. The second element is the
-    chosen path.
+    A 2-tuple. The first element is None or 'external', depending on whether
+    local_path or external_path was chosen. The second element is the chosen
+    path.
   """
   if os.path.exists(local_path) or not os.path.exists(external_path):
-    return ('standalone', local_path)
+    return (None, local_path)
   return ('external', external_path)
 
 
@@ -64,7 +64,8 @@ def main(args):
                    'mini_chromium', 'build', 'common.gypi'),
       os.path.join(crashpad_dir, os.pardir, os.pardir, 'mini_chromium',
                    'mini_chromium', 'build', 'common.gypi')))
-  args.extend(['-D', 'crashpad_dependencies=%s' % dependencies])
+  if dependencies is not None:
+    args.extend(['-D', 'crashpad_dependencies=%s' % dependencies])
   args.extend(['--include', mini_chromium_dir])
   args.extend(['--depth', crashpad_dir_or_dot])
   args.append(os.path.join(crashpad_dir, 'crashpad.gyp'))
diff --git a/handler/crash_report_upload_thread.cc b/handler/crash_report_upload_thread.cc
index 5bd1fbf9..2c2b69b9 100644
--- a/handler/crash_report_upload_thread.cc
+++ b/handler/crash_report_upload_thread.cc
@@ -139,7 +139,8 @@ class CallRecordUploadAttempt {
 
 CrashReportUploadThread::CrashReportUploadThread(CrashReportDatabase* database,
                                                  const std::string& url,
-                                                 bool rate_limit)
+                                                 bool rate_limit,
+                                                 bool upload_gzip)
     : url_(url),
       // Check for pending reports every 15 minutes, even in the absence of a
       // signal from the handler thread. This allows for failed uploads to be
@@ -147,7 +148,8 @@ CrashReportUploadThread::CrashReportUploadThread(CrashReportDatabase* database,
       // processes to be recognized.
       thread_(15 * 60, this),
       database_(database),
-      rate_limit_(rate_limit) {
+      rate_limit_(rate_limit),
+      upload_gzip_(upload_gzip) {
 }
 
 CrashReportUploadThread::~CrashReportUploadThread() {
@@ -308,6 +310,7 @@ CrashReportUploadThread::UploadResult CrashReportUploadThread::UploadReport(
   }
 
   HTTPMultipartBuilder http_multipart_builder;
+  http_multipart_builder.SetGzipEnabled(upload_gzip_);
 
   const char kMinidumpKey[] = "upload_file_minidump";
 
@@ -332,9 +335,11 @@ CrashReportUploadThread::UploadResult CrashReportUploadThread::UploadReport(
 
   std::unique_ptr<HTTPTransport> http_transport(HTTPTransport::Create());
   http_transport->SetURL(url_);
-  HTTPHeaders::value_type content_type =
-      http_multipart_builder.GetContentType();
-  http_transport->SetHeader(content_type.first, content_type.second);
+  HTTPHeaders content_headers;
+  http_multipart_builder.PopulateContentHeaders(&content_headers);
+  for (const auto& content_header : content_headers) {
+    http_transport->SetHeader(content_header.first, content_header.second);
+  }
   http_transport->SetBodyStream(http_multipart_builder.GetBodyStream());
   // TODO(mark): The timeout should be configurable by the client.
   http_transport->SetTimeout(60.0);  // 1 minute.
diff --git a/handler/crash_report_upload_thread.h b/handler/crash_report_upload_thread.h
index a9601d14..14debacd 100644
--- a/handler/crash_report_upload_thread.h
+++ b/handler/crash_report_upload_thread.h
@@ -45,9 +45,11 @@ class CrashReportUploadThread : public WorkerThread::Delegate {
   //! \param[in] url The URL of the server to upload crash reports to.
   //! \param[in] rate_limit Whether uploads should be throttled to a (currently
   //!     hardcoded) rate.
+  //! \param[in] upload_gzip Whether uploads should use `gzip` compression.
   CrashReportUploadThread(CrashReportDatabase* database,
                           const std::string& url,
-                          bool rate_limit);
+                          bool rate_limit,
+                          bool upload_gzip);
   ~CrashReportUploadThread();
 
   //! \brief Starts a dedicated upload thread, which executes ThreadMain().
@@ -139,6 +141,7 @@ class CrashReportUploadThread : public WorkerThread::Delegate {
   WorkerThread thread_;
   CrashReportDatabase* database_;  // weak
   bool rate_limit_;
+  bool upload_gzip_;
 
   DISALLOW_COPY_AND_ASSIGN(CrashReportUploadThread);
 };
diff --git a/handler/crashpad_handler.md b/handler/crashpad_handler.md
index 31c0b347..30dacfe7 100644
--- a/handler/crashpad_handler.md
+++ b/handler/crashpad_handler.md
@@ -144,6 +144,14 @@ establish the Crashpad client environment before running a program.
    throttled to one per hour. Using this option disables that behavior, and
    Crashpad will attempt to upload all captured reports.
 
+ * **--no-upload-gzip**
+
+   Do not use `gzip` compression for uploaded crash reports. Normally, the
+   entire request body is compressed into a `gzip` stream and transmitted with
+   `Content-Encoding: gzip`. This option disables compression, and is intended
+   for use with collection servers that don’t accept uploads compressed in this
+   way.
+
  * **--pipe-name**=_PIPE_
 
    Listen on the given pipe name for connections from clients. _PIPE_ must be of
diff --git a/handler/handler.gyp b/handler/handler.gyp
index e2d993df..6a51222c 100644
--- a/handler/handler.gyp
+++ b/handler/handler.gyp
@@ -15,7 +15,6 @@
 {
   'includes': [
     '../build/crashpad.gypi',
-    '../build/crashpad_dependencies.gypi',
   ],
   'targets': [
     {
@@ -66,29 +65,6 @@
       ],
 
       'conditions': [
-        ['OS=="mac"', {
-          # In an in-Chromium build with component=shared_library,
-          # crashpad_handler will depend on shared libraries such as
-          # libbase.dylib located in out/{Debug,Release} via the @rpath
-          # mechanism. When crashpad_handler is copied to its home deep inside
-          # the Chromium app bundle, it needs to have an LC_RPATH command
-          # pointing back to the directory containing these dependency
-          # libraries.
-          'variables': {
-            'component%': 'static_library',
-          },
-          'conditions': [
-            ['crashpad_dependencies=="chromium" and component=="shared_library"', {
-              'xcode_settings': {
-                'LD_RUNPATH_SEARCH_PATHS': [  # -Wl,-rpath
-                  # Get back from
-                  # Chromium.app/Contents/Versions/V/Framework.framework/Helpers
-                  '@loader_path/../../../../../..',
-                ],
-              },
-            }],
-          ],
-        }],
         ['OS=="win"',  {
           'msvs_settings': {
             'VCLinkerTool': {
diff --git a/handler/handler_main.cc b/handler/handler_main.cc
index 9433a6af..c7c2b297 100644
--- a/handler/handler_main.cc
+++ b/handler/handler_main.cc
@@ -24,8 +24,10 @@
 #include <memory>
 #include <string>
 #include <utility>
+#include <vector>
 
 #include "base/auto_reset.h"
+#include "base/compiler_specific.h"
 #include "base/files/file_path.h"
 #include "base/files/scoped_file.h"
 #include "base/logging.h"
@@ -64,6 +66,7 @@
 #include "util/win/exception_handler_server.h"
 #include "util/win/handle.h"
 #include "util/win/initial_client_data.h"
+#include "util/win/session_end_watcher.h"
 #endif  // OS_MACOSX
 
 namespace crashpad {
@@ -93,6 +96,7 @@ void Usage(const base::FilePath& me) {
 #endif  // OS_MACOSX
 "      --metrics-dir=DIR       store metrics files in DIR (only in Chromium)\n"
 "      --no-rate-limit         don't rate limit crash uploads\n"
+"      --no-upload-gzip        don't use gzip compression when uploading\n"
 #if defined(OS_MACOSX)
 "      --reset-own-crash-exception-port-to-system-default\n"
 "                              reset the server's exception handler to default\n"
@@ -107,11 +111,65 @@ void Usage(const base::FilePath& me) {
   ToolSupport::UsageTail(me);
 }
 
+// Calls Metrics::HandlerLifetimeMilestone, but only on the first call. This is
+// to prevent multiple exit events from inadvertently being recorded, which
+// might happen if a crash occurs during destruction in what would otherwise be
+// a normal exit, or if a CallMetricsRecordNormalExit object is destroyed after
+// something else logs an exit event.
+void MetricsRecordExit(Metrics::LifetimeMilestone milestone) {
+  static bool once = [](Metrics::LifetimeMilestone milestone) {
+    Metrics::HandlerLifetimeMilestone(milestone);
+    return true;
+  }(milestone);
+  ALLOW_UNUSED_LOCAL(once);
+}
+
+// Calls MetricsRecordExit() to record a failure, and returns EXIT_FAILURE for
+// the convenience of callers in main() which can simply write “return
+// ExitFailure();”.
+int ExitFailure() {
+  MetricsRecordExit(Metrics::LifetimeMilestone::kFailed);
+  return EXIT_FAILURE;
+}
+
+class CallMetricsRecordNormalExit {
+ public:
+  CallMetricsRecordNormalExit() {}
+  ~CallMetricsRecordNormalExit() {
+    MetricsRecordExit(Metrics::LifetimeMilestone::kExitedNormally);
+  }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(CallMetricsRecordNormalExit);
+};
+
 #if defined(OS_MACOSX)
 
-struct sigaction g_original_crash_sigaction[NSIG];
+void InstallSignalHandler(const std::vector<int>& signals,
+                          void (*handler)(int, siginfo_t*, void*)) {
+  struct sigaction sa = {};
+  sigemptyset(&sa.sa_mask);
+  sa.sa_flags = SA_SIGINFO;
+  sa.sa_sigaction = handler;
+
+  for (int sig : signals) {
+    int rv = sigaction(sig, &sa, nullptr);
+    PCHECK(rv == 0) << "sigaction " << sig;
+  }
+}
+
+void RestoreDefaultSignalHandler(int sig) {
+  struct sigaction sa = {};
+  sigemptyset(&sa.sa_mask);
+  sa.sa_flags = 0;
+  sa.sa_handler = SIG_DFL;
+  int rv = sigaction(sig, &sa, nullptr);
+  DPLOG_IF(ERROR, rv != 0) << "sigaction " << sig;
+}
 
 void HandleCrashSignal(int sig, siginfo_t* siginfo, void* context) {
+  MetricsRecordExit(Metrics::LifetimeMilestone::kCrashed);
+
   // Is siginfo->si_code useful? The only interesting values on macOS are 0 (not
   // useful, signals generated asynchronously such as by kill() or raise()) and
   // small positive numbers (useful, signal generated via a hardware fault). The
@@ -143,22 +201,17 @@ void HandleCrashSignal(int sig, siginfo_t* siginfo, void* context) {
   }
   Metrics::HandlerCrashed(metrics_code);
 
-  // Restore the previous signal handler.
-  DCHECK_GT(sig, 0);
-  DCHECK_LT(static_cast<size_t>(sig), arraysize(g_original_crash_sigaction));
-  struct sigaction* osa = &g_original_crash_sigaction[sig];
-  int rv = sigaction(sig, osa, nullptr);
-  DPLOG_IF(ERROR, rv != 0) << "sigaction " << sig;
+  RestoreDefaultSignalHandler(sig);
 
   // If the signal was received synchronously resulting from a hardware fault,
   // returning from the signal handler will cause the kernel to re-raise it,
   // because this handler hasn’t done anything to alleviate the condition that
-  // caused the signal to be raised in the first place. With the old signal
-  // handler in place (expected to be SIG_DFL), it will cause the same behavior
-  // to be taken as though this signal handler had never been installed at all
-  // (expected to be a crash). This is ideal, because the signal is re-raised
-  // with the same properties and from the same context that initially triggered
-  // it, providing the best debugging experience.
+  // caused the signal to be raised in the first place. With the default signal
+  // handler in place, it will cause the same behavior to be taken as though
+  // this signal handler had never been installed at all (expected to be a
+  // crash). This is ideal, because the signal is re-raised with the same
+  // properties and from the same context that initially triggered it, providing
+  // the best debugging experience.
 
   if ((sig != SIGILL && sig != SIGFPE && sig != SIGBUS && sig != SIGSEGV) ||
       !si_code_valid) {
@@ -166,8 +219,7 @@ void HandleCrashSignal(int sig, siginfo_t* siginfo, void* context) {
     // asynchronously via kill() and raise(), and those arising via hardware
     // traps such as int3 (resulting in SIGTRAP but advancing the instruction
     // pointer), will not reoccur on their own when returning from the signal
-    // handler. Re-raise them or call to the previous signal handler as
-    // appropriate.
+    // handler. Re-raise them.
     //
     // Unfortunately, when SIGBUS is received asynchronously via kill(),
     // siginfo->si_code makes it appear as though it was actually received via a
@@ -180,49 +232,66 @@ void HandleCrashSignal(int sig, siginfo_t* siginfo, void* context) {
     // very valuable for debugging and are visible to a Mach exception handler.
     // Since SIGBUS is normally received synchronously in response to a hardware
     // fault, don’t sweat the unexpected asynchronous case.
-    if (osa->sa_handler == SIG_DFL) {
-      // Because this signal handler executes with the signal blocked, this
-      // raise() cannot immediately deliver the signal. Delivery is deferred
-      // until this signal handler returns and the signal becomes unblocked. The
-      // re-raised signal will appear with the same context as where it was
-      // initially triggered.
-      rv = raise(sig);
-      DPLOG_IF(ERROR, rv != 0) << "raise";
-    } else if (osa->sa_handler != SIG_IGN) {
-      if (osa->sa_flags & SA_SIGINFO) {
-        osa->sa_sigaction(sig, siginfo, context);
-      } else {
-        osa->sa_handler(sig);
-      }
-    }
+    //
+    // Because this signal handler executes with the signal blocked, this
+    // raise() cannot immediately deliver the signal. Delivery is deferred until
+    // this signal handler returns and the signal becomes unblocked. The
+    // re-raised signal will appear with the same context as where it was
+    // initially triggered.
+    int rv = raise(sig);
+    DPLOG_IF(ERROR, rv != 0) << "raise";
   }
 }
 
-void InstallCrashHandler() {
-  struct sigaction sa = {};
-  sigemptyset(&sa.sa_mask);
-  sa.sa_flags = SA_SIGINFO;
-  sa.sa_sigaction = HandleCrashSignal;
+void HandleTerminateSignal(int sig, siginfo_t* siginfo, void* context) {
+  MetricsRecordExit(Metrics::LifetimeMilestone::kTerminated);
 
+  RestoreDefaultSignalHandler(sig);
+
+  // Re-raise the signal. See the explanation in HandleCrashSignal(). Note that
+  // no checks for signals arising from synchronous hardware faults are made
+  // because termination signals never originate in that way.
+  int rv = raise(sig);
+  DPLOG_IF(ERROR, rv != 0) << "raise";
+}
+
+void InstallCrashHandler() {
   // These are the core-generating signals from 10.12.3
   // xnu-3789.41.3/bsd/sys/signalvar.h sigprop: entries with SA_CORE are in the
   // set.
-  const int kSignals[] = {SIGQUIT,
-                          SIGILL,
-                          SIGTRAP,
-                          SIGABRT,
-                          SIGEMT,
-                          SIGFPE,
-                          SIGBUS,
-                          SIGSEGV,
-                          SIGSYS};
+  const int kCrashSignals[] = {SIGQUIT,
+                               SIGILL,
+                               SIGTRAP,
+                               SIGABRT,
+                               SIGEMT,
+                               SIGFPE,
+                               SIGBUS,
+                               SIGSEGV,
+                               SIGSYS};
+  InstallSignalHandler(
+      std::vector<int>(&kCrashSignals[0],
+                       &kCrashSignals[arraysize(kCrashSignals)]),
+      HandleCrashSignal);
 
-  for (int sig : kSignals) {
-    DCHECK_GT(sig, 0);
-    DCHECK_LT(static_cast<size_t>(sig), arraysize(g_original_crash_sigaction));
-    int rv = sigaction(sig, &sa, &g_original_crash_sigaction[sig]);
-    PCHECK(rv == 0) << "sigaction " << sig;
-  }
+  // Not a crash handler, but close enough. These are non-core-generating but
+  // terminating signals from 10.12.3 xnu-3789.41.3/bsd/sys/signalvar.h sigprop:
+  // entries with SA_KILL but not SA_CORE are in the set. SIGKILL is excluded
+  // because it is uncatchable.
+  const int kTerminateSignals[] = {SIGHUP,
+                                   SIGINT,
+                                   SIGPIPE,
+                                   SIGALRM,
+                                   SIGTERM,
+                                   SIGXCPU,
+                                   SIGXFSZ,
+                                   SIGVTALRM,
+                                   SIGPROF,
+                                   SIGUSR1,
+                                   SIGUSR2};
+  InstallSignalHandler(
+      std::vector<int>(&kTerminateSignals[0],
+                       &kTerminateSignals[arraysize(kTerminateSignals)]),
+      HandleTerminateSignal);
 }
 
 struct ResetSIGTERMTraits {
@@ -242,6 +311,9 @@ ExceptionHandlerServer* g_exception_handler_server;
 
 // This signal handler is only operative when being run from launchd.
 void HandleSIGTERM(int sig, siginfo_t* siginfo, void* context) {
+  // Don’t call MetricsRecordExit(). This is part of the normal exit path when
+  // running from launchd.
+
   DCHECK(g_exception_handler_server);
   g_exception_handler_server->Stop();
 }
@@ -251,6 +323,7 @@ void HandleSIGTERM(int sig, siginfo_t* siginfo, void* context) {
 LONG(WINAPI* g_original_exception_filter)(EXCEPTION_POINTERS*) = nullptr;
 
 LONG WINAPI UnhandledExceptionHandler(EXCEPTION_POINTERS* exception_pointers) {
+  MetricsRecordExit(Metrics::LifetimeMilestone::kCrashed);
   Metrics::HandlerCrashed(exception_pointers->ExceptionRecord->ExceptionCode);
 
   if (g_original_exception_filter)
@@ -259,9 +332,37 @@ LONG WINAPI UnhandledExceptionHandler(EXCEPTION_POINTERS* exception_pointers) {
     return EXCEPTION_CONTINUE_SEARCH;
 }
 
+// Handles events like Control-C and Control-Break on a console.
+BOOL WINAPI ConsoleHandler(DWORD console_event) {
+  MetricsRecordExit(Metrics::LifetimeMilestone::kTerminated);
+  return false;
+}
+
+// Handles a WM_ENDSESSION message sent when the user session is ending.
+class TerminateHandler final : public SessionEndWatcher {
+ public:
+  TerminateHandler() : SessionEndWatcher() {}
+  ~TerminateHandler() override {}
+
+ private:
+  // SessionEndWatcher:
+  void SessionEnding() override {
+    MetricsRecordExit(Metrics::LifetimeMilestone::kTerminated);
+  }
+
+  DISALLOW_COPY_AND_ASSIGN(TerminateHandler);
+};
+
 void InstallCrashHandler() {
   g_original_exception_filter =
       SetUnhandledExceptionFilter(&UnhandledExceptionHandler);
+
+  // These are termination handlers, not crash handlers, but that’s close
+  // enough. Note that destroying the TerminateHandler would wait for its thread
+  // to exit, which isn’t necessary or desirable.
+  SetConsoleCtrlHandler(ConsoleHandler, true);
+  static TerminateHandler* terminate_handler = new TerminateHandler();
+  ALLOW_UNUSED_LOCAL(terminate_handler);
 }
 
 #endif  // OS_MACOSX
@@ -270,6 +371,7 @@ void InstallCrashHandler() {
 
 int HandlerMain(int argc, char* argv[]) {
   InstallCrashHandler();
+  CallMetricsRecordNormalExit metrics_record_normal_exit;
 
   const base::FilePath argv0(
       ToolSupport::CommandLineArgumentToFilePathStringType(argv[0]));
@@ -291,6 +393,7 @@ int HandlerMain(int argc, char* argv[]) {
 #endif  // OS_MACOSX
     kOptionMetrics,
     kOptionNoRateLimit,
+    kOptionNoUploadGzip,
 #if defined(OS_MACOSX)
     kOptionResetOwnCrashExceptionPortToSystemDefault,
 #elif defined(OS_WIN)
@@ -317,11 +420,13 @@ int HandlerMain(int argc, char* argv[]) {
     InitialClientData initial_client_data;
 #endif  // OS_MACOSX
     bool rate_limit;
+    bool upload_gzip;
   } options = {};
 #if defined(OS_MACOSX)
   options.handshake_fd = -1;
 #endif
   options.rate_limit = true;
+  options.upload_gzip = true;
 
   const option long_options[] = {
     {"annotation", required_argument, nullptr, kOptionAnnotation},
@@ -340,6 +445,7 @@ int HandlerMain(int argc, char* argv[]) {
 #endif  // OS_MACOSX
     {"metrics-dir", required_argument, nullptr, kOptionMetrics},
     {"no-rate-limit", no_argument, nullptr, kOptionNoRateLimit},
+    {"no-upload-gzip", no_argument, nullptr, kOptionNoUploadGzip},
 #if defined(OS_MACOSX)
     {"reset-own-crash-exception-port-to-system-default",
      no_argument,
@@ -362,7 +468,7 @@ int HandlerMain(int argc, char* argv[]) {
         std::string value;
         if (!SplitStringFirst(optarg, '=', &key, &value)) {
           ToolSupport::UsageHint(me, "--annotation requires KEY=VALUE");
-          return EXIT_FAILURE;
+          return ExitFailure();
         }
         std::string old_value;
         if (!MapInsertOrReplace(&options.annotations, key, value, &old_value)) {
@@ -381,7 +487,7 @@ int HandlerMain(int argc, char* argv[]) {
             options.handshake_fd < 0) {
           ToolSupport::UsageHint(me,
                                  "--handshake-fd requires a file descriptor");
-          return EXIT_FAILURE;
+          return ExitFailure();
         }
         break;
       }
@@ -394,7 +500,7 @@ int HandlerMain(int argc, char* argv[]) {
         if (!options.initial_client_data.InitializeFromString(optarg)) {
           ToolSupport::UsageHint(
               me, "failed to parse --initial-client-data");
-          return EXIT_FAILURE;
+          return ExitFailure();
         }
         break;
       }
@@ -407,6 +513,10 @@ int HandlerMain(int argc, char* argv[]) {
         options.rate_limit = false;
         break;
       }
+      case kOptionNoUploadGzip: {
+        options.upload_gzip = false;
+        break;
+      }
 #if defined(OS_MACOSX)
       case kOptionResetOwnCrashExceptionPortToSystemDefault: {
         options.reset_own_crash_exception_port_to_system_default = true;
@@ -424,15 +534,17 @@ int HandlerMain(int argc, char* argv[]) {
       }
       case kOptionHelp: {
         Usage(me);
+        MetricsRecordExit(Metrics::LifetimeMilestone::kExitedEarly);
         return EXIT_SUCCESS;
       }
       case kOptionVersion: {
         ToolSupport::Version(me);
+        MetricsRecordExit(Metrics::LifetimeMilestone::kExitedEarly);
         return EXIT_SUCCESS;
       }
       default: {
         ToolSupport::UsageHint(me, nullptr);
-        return EXIT_FAILURE;
+        return ExitFailure();
       }
     }
   }
@@ -442,34 +554,34 @@ int HandlerMain(int argc, char* argv[]) {
 #if defined(OS_MACOSX)
   if (options.handshake_fd < 0 && options.mach_service.empty()) {
     ToolSupport::UsageHint(me, "--handshake-fd or --mach-service is required");
-    return EXIT_FAILURE;
+    return ExitFailure();
   }
   if (options.handshake_fd >= 0 && !options.mach_service.empty()) {
     ToolSupport::UsageHint(
         me, "--handshake-fd and --mach-service are incompatible");
-    return EXIT_FAILURE;
+    return ExitFailure();
   }
 #elif defined(OS_WIN)
   if (!options.initial_client_data.IsValid() && options.pipe_name.empty()) {
     ToolSupport::UsageHint(me,
                            "--initial-client-data or --pipe-name is required");
-    return EXIT_FAILURE;
+    return ExitFailure();
   }
   if (options.initial_client_data.IsValid() && !options.pipe_name.empty()) {
     ToolSupport::UsageHint(
         me, "--initial-client-data and --pipe-name are incompatible");
-    return EXIT_FAILURE;
+    return ExitFailure();
   }
 #endif  // OS_MACOSX
 
   if (!options.database) {
     ToolSupport::UsageHint(me, "--database is required");
-    return EXIT_FAILURE;
+    return ExitFailure();
   }
 
   if (argc) {
     ToolSupport::UsageHint(me, nullptr);
-    return EXIT_FAILURE;
+    return ExitFailure();
   }
 
 #if defined(OS_MACOSX)
@@ -494,7 +606,7 @@ int HandlerMain(int argc, char* argv[]) {
   }
 
   if (!receive_right.is_valid()) {
-    return EXIT_FAILURE;
+    return ExitFailure();
   }
 
   ExceptionHandlerServer exception_handler_server(
@@ -511,6 +623,7 @@ int HandlerMain(int argc, char* argv[]) {
     // launchd.plist(5).
     //
     // Set up a SIGTERM handler that will call exception_handler_server.Stop().
+    // This replaces the HandleTerminateSignal handler for SIGTERM.
     struct sigaction sa = {};
     sigemptyset(&sa.sa_mask);
     sa.sa_flags = SA_SIGINFO;
@@ -544,18 +657,20 @@ int HandlerMain(int argc, char* argv[]) {
     }
   }
 
+  Metrics::HandlerLifetimeMilestone(Metrics::LifetimeMilestone::kStarted);
+
   std::unique_ptr<CrashReportDatabase> database(CrashReportDatabase::Initialize(
       base::FilePath(ToolSupport::CommandLineArgumentToFilePathStringType(
           options.database))));
   if (!database) {
-    return EXIT_FAILURE;
+    return ExitFailure();
   }
 
   // TODO(scottmg): options.rate_limit should be removed when we have a
   // configurable database setting to control upload limiting.
   // See https://crashpad.chromium.org/bug/23.
   CrashReportUploadThread upload_thread(
-      database.get(), options.url, options.rate_limit);
+      database.get(), options.url, options.rate_limit, options.upload_gzip);
   upload_thread.Start();
 
   PruneCrashReportThread prune_thread(database.get(),
diff --git a/minidump/minidump_context.h b/minidump/minidump_context.h
index 4eb3acfa..b71b57cc 100644
--- a/minidump/minidump_context.h
+++ b/minidump/minidump_context.h
@@ -92,7 +92,8 @@ enum MinidumpContextX86Flags : uint32_t {
   //! \brief Indicates the validity of floating-point state
   //!     (`CONTEXT_FLOATING_POINT`).
   //!
-  //! The `float_save` field is valid.
+  //! The `fsave` field is valid. The `float_save` field is included in this
+  //! definition, but its members have no practical use asdie from `fsave`.
   kMinidumpContextX86FloatingPoint = kMinidumpContextX86 | 0x00000008,
 
   //! \brief Indicates the validity of debug registers
@@ -130,8 +131,9 @@ enum MinidumpContextX86Flags : uint32_t {
 //! \brief A 32-bit x86 CPU context (register state) carried in a minidump file.
 //!
 //! This is analogous to the `CONTEXT` structure on Windows when targeting
-//! 32-bit x86. This structure is used instead of `CONTEXT` to make it available
-//! when targeting other architectures.
+//! 32-bit x86, and the `WOW64_CONTEXT` structure when targeting an x86-family
+//! CPU, either 32- or 64-bit. This structure is used instead of `CONTEXT` or
+//! `WOW64_CONTEXT` to make it available when targeting other architectures.
 //!
 //! \note This structure doesn’t carry `dr4` or `dr5`, which are obsolete and
 //!     normally alias `dr6` and `dr7`, respectively. See Intel Software
@@ -152,16 +154,12 @@ struct MinidumpContextX86 {
   uint32_t dr6;
   uint32_t dr7;
 
-  struct {
-    uint32_t control_word;
-    uint32_t status_word;
-    uint32_t tag_word;
-    uint32_t error_offset;
-    uint32_t error_selector;
-    uint32_t data_offset;
-    uint32_t data_selector;
-    uint8_t register_area[80];
-    uint32_t spare_0;
+  // CPUContextX86::Fsave has identical layout to what the x86 CONTEXT
+  // structure places here.
+  CPUContextX86::Fsave fsave;
+  union {
+    uint32_t spare_0;  // As in the native x86 CONTEXT structure since Windows 8
+    uint32_t cr0_npx_state;  // As in WOW64_CONTEXT and older SDKs’ x86 CONTEXT
   } float_save;
 
   uint32_t gs;
diff --git a/minidump/minidump_context_writer.cc b/minidump/minidump_context_writer.cc
index 4d3bf8a4..c6c29d96 100644
--- a/minidump/minidump_context_writer.cc
+++ b/minidump/minidump_context_writer.cc
@@ -14,6 +14,8 @@
 
 #include "minidump/minidump_context_writer.h"
 
+#include <windows.h>
+#include <dbghelp.h>
 #include <stdint.h>
 #include <string.h>
 
@@ -24,6 +26,28 @@
 
 namespace crashpad {
 
+namespace {
+
+// Sanity-check complex structures to ensure interoperability.
+static_assert(sizeof(MinidumpContextX86) == 716, "MinidumpContextX86 size");
+static_assert(sizeof(MinidumpContextAMD64) == 1232,
+              "MinidumpContextAMD64 size");
+
+// These structures can also be checked against definitions in the Windows SDK.
+#if defined(OS_WIN)
+#if defined(ARCH_CPU_X86_FAMILY)
+static_assert(sizeof(MinidumpContextX86) == sizeof(WOW64_CONTEXT),
+              "WOW64_CONTEXT size");
+#if defined(ARCH_CPU_X86)
+static_assert(sizeof(MinidumpContextX86) == sizeof(CONTEXT), "CONTEXT size");
+#elif defined(ARCH_CPU_X86_64)
+static_assert(sizeof(MinidumpContextAMD64) == sizeof(CONTEXT), "CONTEXT size");
+#endif
+#endif  // ARCH_CPU_X86_FAMILY
+#endif  // OS_WIN
+
+}  // namespace
+
 MinidumpContextWriter::~MinidumpContextWriter() {
 }
 
@@ -89,28 +113,11 @@ void MinidumpContextX86Writer::InitializeFromSnapshot(
   context_.dr6 = context_snapshot->dr6;
   context_.dr7 = context_snapshot->dr7;
 
-  // The contents of context_.float_save effectively alias everything in
-  // context_.fxsave that’s related to x87 FPU state. context_.float_save
-  // doesn’t carry state specific to SSE (or later), such as mxcsr and the xmm
+  // The contents of context_.fsave effectively alias everything in
+  // context_.fxsave that’s related to x87 FPU state. context_.fsave doesn’t
+  // carry state specific to SSE (or later), such as mxcsr and the xmm
   // registers.
-  context_.float_save.control_word = context_snapshot->fxsave.fcw;
-  context_.float_save.status_word = context_snapshot->fxsave.fsw;
-  context_.float_save.tag_word =
-      CPUContextX86::FxsaveToFsaveTagWord(context_snapshot->fxsave.fsw,
-                                          context_snapshot->fxsave.ftw,
-                                          context_snapshot->fxsave.st_mm);
-  context_.float_save.error_offset = context_snapshot->fxsave.fpu_ip;
-  context_.float_save.error_selector = context_snapshot->fxsave.fpu_cs;
-  context_.float_save.data_offset = context_snapshot->fxsave.fpu_dp;
-  context_.float_save.data_selector = context_snapshot->fxsave.fpu_ds;
-
-  for (size_t index = 0, offset = 0;
-       index < arraysize(context_snapshot->fxsave.st_mm);
-       offset += sizeof(context_snapshot->fxsave.st_mm[index].st), ++index) {
-    memcpy(&context_.float_save.register_area[offset],
-           &context_snapshot->fxsave.st_mm[index].st,
-           sizeof(context_snapshot->fxsave.st_mm[index].st));
-  }
+  CPUContextX86::FxsaveToFsave(context_snapshot->fxsave, &context_.fsave);
 
   context_.gs = context_snapshot->gs;
   context_.fs = context_snapshot->fs;
diff --git a/minidump/test/minidump_context_test_util.cc b/minidump/test/minidump_context_test_util.cc
index 730c2b79..8999abe0 100644
--- a/minidump/test/minidump_context_test_util.cc
+++ b/minidump/test/minidump_context_test_util.cc
@@ -23,6 +23,7 @@
 #include "gtest/gtest.h"
 #include "snapshot/cpu_context.h"
 #include "snapshot/test/test_cpu_context.h"
+#include "test/hex_string.h"
 
 namespace crashpad {
 namespace test {
@@ -56,6 +57,7 @@ void InitializeMinidumpContextX86(MinidumpContextX86* context, uint32_t seed) {
   context->ss = value++ & 0xffff;
 
   InitializeCPUContextX86Fxsave(&context->fxsave, &value);
+  CPUContextX86::FxsaveToFsave(context->fxsave, &context->fsave);
 
   context->dr0 = value++;
   context->dr1 = value++;
@@ -65,30 +67,6 @@ void InitializeMinidumpContextX86(MinidumpContextX86* context, uint32_t seed) {
   context->dr6 = value++;
   context->dr7 = value++;
 
-  // Copy the values that are aliased between the fxsave area
-  // (context->extended_registers) and the floating-point save area
-  // (context->float_save).
-  context->float_save.control_word = context->fxsave.fcw;
-  context->float_save.status_word = context->fxsave.fsw;
-  context->float_save.tag_word = CPUContextX86::FxsaveToFsaveTagWord(
-      context->fxsave.fsw, context->fxsave.ftw, context->fxsave.st_mm);
-  context->float_save.error_offset = context->fxsave.fpu_ip;
-  context->float_save.error_selector = context->fxsave.fpu_cs;
-  context->float_save.data_offset = context->fxsave.fpu_dp;
-  context->float_save.data_selector = context->fxsave.fpu_ds;
-  for (size_t st_mm_index = 0;
-       st_mm_index < arraysize(context->fxsave.st_mm);
-       ++st_mm_index) {
-    for (size_t byte = 0;
-         byte < arraysize(context->fxsave.st_mm[st_mm_index].st);
-         ++byte) {
-      size_t st_index =
-          st_mm_index * arraysize(context->fxsave.st_mm[st_mm_index].st) + byte;
-      context->float_save.register_area[st_index] =
-          context->fxsave.st_mm[st_mm_index].st[byte];
-    }
-  }
-
   // Set this field last, because it has no analogue in CPUContextX86.
   context->float_save.spare_0 = value++;
 }
@@ -188,37 +166,31 @@ void ExpectMinidumpContextFxsave(const FxsaveType* expected,
        st_mm_index < arraysize(expected->st_mm);
        ++st_mm_index) {
     SCOPED_TRACE(base::StringPrintf("st_mm_index %" PRIuS, st_mm_index));
-    for (size_t byte = 0;
-         byte < arraysize(expected->st_mm[st_mm_index].st);
-         ++byte) {
-      EXPECT_EQ(expected->st_mm[st_mm_index].st[byte],
-                observed->st_mm[st_mm_index].st[byte]) << "byte " << byte;
-    }
-    for (size_t byte = 0;
-         byte < arraysize(expected->st_mm[st_mm_index].st_reserved);
-         ++byte) {
-      EXPECT_EQ(expected->st_mm[st_mm_index].st_reserved[byte],
-                observed->st_mm[st_mm_index].st_reserved[byte])
-          << "byte " << byte;
-    }
+    EXPECT_EQ(BytesToHexString(expected->st_mm[st_mm_index].st,
+                               arraysize(expected->st_mm[st_mm_index].st)),
+              BytesToHexString(observed->st_mm[st_mm_index].st,
+                               arraysize(observed->st_mm[st_mm_index].st)));
+    EXPECT_EQ(
+        BytesToHexString(expected->st_mm[st_mm_index].st_reserved,
+                         arraysize(expected->st_mm[st_mm_index].st_reserved)),
+        BytesToHexString(observed->st_mm[st_mm_index].st_reserved,
+                         arraysize(observed->st_mm[st_mm_index].st_reserved)));
   }
   for (size_t xmm_index = 0;
        xmm_index < arraysize(expected->xmm);
        ++xmm_index) {
-    SCOPED_TRACE(base::StringPrintf("xmm_index %" PRIuS, xmm_index));
-    for (size_t byte = 0; byte < arraysize(expected->xmm[xmm_index]); ++byte) {
-      EXPECT_EQ(expected->xmm[xmm_index][byte], observed->xmm[xmm_index][byte])
-          << "byte " << byte;
-    }
-  }
-  for (size_t byte = 0; byte < arraysize(expected->reserved_4); ++byte) {
-    EXPECT_EQ(expected->reserved_4[byte], observed->reserved_4[byte])
-        << "byte " << byte;
-  }
-  for (size_t byte = 0; byte < arraysize(expected->available); ++byte) {
-    EXPECT_EQ(expected->available[byte], observed->available[byte])
-        << "byte " << byte;
+    EXPECT_EQ(BytesToHexString(expected->xmm[xmm_index],
+                               arraysize(expected->xmm[xmm_index])),
+              BytesToHexString(observed->xmm[xmm_index],
+                               arraysize(observed->xmm[xmm_index])))
+        << "xmm_index " << xmm_index;
   }
+  EXPECT_EQ(
+      BytesToHexString(expected->reserved_4, arraysize(expected->reserved_4)),
+      BytesToHexString(observed->reserved_4, arraysize(observed->reserved_4)));
+  EXPECT_EQ(
+      BytesToHexString(expected->available, arraysize(expected->available)),
+      BytesToHexString(observed->available, arraysize(observed->available)));
 }
 
 }  // namespace
@@ -236,22 +208,19 @@ void ExpectMinidumpContextX86(
   EXPECT_EQ(expected.dr6, observed->dr6);
   EXPECT_EQ(expected.dr7, observed->dr7);
 
-  EXPECT_EQ(expected.float_save.control_word,
-            observed->float_save.control_word);
-  EXPECT_EQ(expected.float_save.status_word, observed->float_save.status_word);
-  EXPECT_EQ(expected.float_save.tag_word, observed->float_save.tag_word);
-  EXPECT_EQ(expected.float_save.error_offset,
-            observed->float_save.error_offset);
-  EXPECT_EQ(expected.float_save.error_selector,
-            observed->float_save.error_selector);
-  EXPECT_EQ(expected.float_save.data_offset, observed->float_save.data_offset);
-  EXPECT_EQ(expected.float_save.data_selector,
-            observed->float_save.data_selector);
-  for (size_t index = 0;
-       index < arraysize(expected.float_save.register_area);
-       ++index) {
-    EXPECT_EQ(expected.float_save.register_area[index],
-              observed->float_save.register_area[index]) << "index " << index;
+  EXPECT_EQ(expected.fsave.fcw, observed->fsave.fcw);
+  EXPECT_EQ(expected.fsave.fsw, observed->fsave.fsw);
+  EXPECT_EQ(expected.fsave.ftw, observed->fsave.ftw);
+  EXPECT_EQ(expected.fsave.fpu_ip, observed->fsave.fpu_ip);
+  EXPECT_EQ(expected.fsave.fpu_cs, observed->fsave.fpu_cs);
+  EXPECT_EQ(expected.fsave.fpu_dp, observed->fsave.fpu_dp);
+  EXPECT_EQ(expected.fsave.fpu_ds, observed->fsave.fpu_ds);
+  for (size_t index = 0; index < arraysize(expected.fsave.st); ++index) {
+    EXPECT_EQ(BytesToHexString(expected.fsave.st[index],
+                               arraysize(expected.fsave.st[index])),
+              BytesToHexString(observed->fsave.st[index],
+                               arraysize(observed->fsave.st[index])))
+        << "index " << index;
   }
   if (snapshot) {
     EXPECT_EQ(0u, observed->float_save.spare_0);
diff --git a/snapshot/cpu_context.cc b/snapshot/cpu_context.cc
index c11a031b..c3887a2c 100644
--- a/snapshot/cpu_context.cc
+++ b/snapshot/cpu_context.cc
@@ -14,23 +14,84 @@
 
 #include "snapshot/cpu_context.h"
 
+#include <string.h>
+
 #include "base/logging.h"
+#include "base/macros.h"
 #include "util/misc/implicit_cast.h"
 
 namespace crashpad {
 
+namespace {
+
+// Sanity-check complex structures to ensure interoperability.
+static_assert(sizeof(CPUContextX86::Fsave) == 108, "CPUContextX86::Fsave size");
+static_assert(sizeof(CPUContextX86::Fxsave) == 512,
+              "CPUContextX86::Fxsave size");
+static_assert(sizeof(CPUContextX86_64::Fxsave) == 512,
+              "CPUContextX86_64::Fxsave size");
+
+enum {
+  kX87TagValid = 0,
+  kX87TagZero,
+  kX87TagSpecial,
+  kX87TagEmpty,
+};
+
+}  // namespace
+
+// static
+void CPUContextX86::FxsaveToFsave(const Fxsave& fxsave, Fsave* fsave) {
+  fsave->fcw = fxsave.fcw;
+  fsave->reserved_1 = 0;
+  fsave->fsw = fxsave.fsw;
+  fsave->reserved_2 = 0;
+  fsave->ftw = FxsaveToFsaveTagWord(fxsave.fsw, fxsave.ftw, fxsave.st_mm);
+  fsave->reserved_3 = 0;
+  fsave->fpu_ip = fxsave.fpu_ip;
+  fsave->fpu_cs = fxsave.fpu_cs;
+  fsave->fop = fxsave.fop;
+  fsave->fpu_dp = fxsave.fpu_dp;
+  fsave->fpu_ds = fxsave.fpu_ds;
+  fsave->reserved_4 = 0;
+  static_assert(arraysize(fsave->st) == arraysize(fxsave.st_mm),
+                "FPU stack registers must be equivalent");
+  for (size_t index = 0; index < arraysize(fsave->st); ++index) {
+    memcpy(fsave->st[index], fxsave.st_mm[index].st, sizeof(fsave->st[index]));
+  }
+}
+
+// static
+void CPUContextX86::FsaveToFxsave(const Fsave& fsave, Fxsave* fxsave) {
+  fxsave->fcw = fsave.fcw;
+  fxsave->fsw = fsave.fsw;
+  fxsave->ftw = FsaveToFxsaveTagWord(fsave.ftw);
+  fxsave->reserved_1 = 0;
+  fxsave->fop = fsave.fop;
+  fxsave->fpu_ip = fsave.fpu_ip;
+  fxsave->fpu_cs = fsave.fpu_cs;
+  fxsave->reserved_2 = 0;
+  fxsave->fpu_dp = fsave.fpu_dp;
+  fxsave->fpu_ds = fsave.fpu_ds;
+  fxsave->reserved_3 = 0;
+  fxsave->mxcsr = 0;
+  fxsave->mxcsr_mask = 0;
+  static_assert(arraysize(fxsave->st_mm) == arraysize(fsave.st),
+                "FPU stack registers must be equivalent");
+  for (size_t index = 0; index < arraysize(fsave.st); ++index) {
+    memcpy(fxsave->st_mm[index].st, fsave.st[index], sizeof(fsave.st[index]));
+    memset(fxsave->st_mm[index].st_reserved,
+           0,
+           sizeof(fxsave->st_mm[index].st_reserved));
+  }
+  memset(fxsave->xmm, 0, sizeof(*fxsave) - offsetof(Fxsave, xmm));
+}
+
 // static
 uint16_t CPUContextX86::FxsaveToFsaveTagWord(
     uint16_t fsw,
     uint8_t fxsave_tag,
     const CPUContextX86::X87OrMMXRegister st_mm[8]) {
-  enum {
-    kX87TagValid = 0,
-    kX87TagZero,
-    kX87TagSpecial,
-    kX87TagEmpty,
-  };
-
   // The x87 tag word (in both abridged and full form) identifies physical
   // registers, but |st_mm| is arranged in logical stack order. In order to map
   // physical tag word bits to the logical stack registers they correspond to,
@@ -85,6 +146,17 @@ uint16_t CPUContextX86::FxsaveToFsaveTagWord(
   return fsave_tag;
 }
 
+// static
+uint8_t CPUContextX86::FsaveToFxsaveTagWord(uint16_t fsave_tag) {
+  uint8_t fxsave_tag = 0;
+  for (int physical_index = 0; physical_index < 8; ++physical_index) {
+    const uint8_t fsave_bits = (fsave_tag >> (physical_index * 2)) & 0x3;
+    const bool fxsave_bit = fsave_bits != kX87TagEmpty;
+    fxsave_tag |= fxsave_bit << physical_index;
+  }
+  return fxsave_tag;
+}
+
 uint64_t CPUContext::InstructionPointer() const {
   switch (architecture) {
     case kCPUArchitectureX86:
diff --git a/snapshot/cpu_context.h b/snapshot/cpu_context.h
index 67b298e8..ba3ac181 100644
--- a/snapshot/cpu_context.h
+++ b/snapshot/cpu_context.h
@@ -25,6 +25,22 @@ namespace crashpad {
 struct CPUContextX86 {
   using X87Register = uint8_t[10];
 
+  struct Fsave {
+    uint16_t fcw;  // FPU control word
+    uint16_t reserved_1;
+    uint16_t fsw;  // FPU status word
+    uint16_t reserved_2;
+    uint16_t ftw;  // full FPU tag word
+    uint16_t reserved_3;
+    uint32_t fpu_ip;  // FPU instruction pointer offset
+    uint16_t fpu_cs;  // FPU instruction pointer segment selector
+    uint16_t fop;  // FPU opcode
+    uint32_t fpu_dp;  // FPU data pointer offset
+    uint16_t fpu_ds;  // FPU data pointer segment selector
+    uint16_t reserved_4;
+    X87Register st[8];
+  };
+
   union X87OrMMXRegister {
     struct {
       X87Register st;
@@ -58,14 +74,49 @@ struct CPUContextX86 {
     uint8_t available[48];
   };
 
+  //! \brief Converts an `fxsave` area to an `fsave` area.
+  //!
+  //! `fsave` state is restricted to the x87 FPU, while `fxsave` state includes
+  //! state related to the x87 FPU as well as state specific to SSE.
+  //!
+  //! As the `fxsave` format is a superset of the `fsave` format, this operation
+  //! fully populates the `fsave` area. `fsave` uses the full 16-bit form for
+  //! the x87 floating-point tag word, so FxsaveToFsaveTagWord() is used to
+  //! derive Fsave::ftw from the abridged 8-bit form used by `fxsave`. Reserved
+  //! fields in \a fsave are set to `0`.
+  //!
+  //! \param[in] fxsave The `fxsave` area to convert.
+  //! \param[out] fsave The `fsave` area to populate.
+  //!
+  //! \sa FsaveToFxsave()
+  static void FxsaveToFsave(const Fxsave& fxsave, Fsave* fsave);
+
+  //! \brief Converts an `fsave` area to an `fxsave` area.
+  //!
+  //! `fsave` state is restricted to the x87 FPU, while `fxsave` state includes
+  //! state related to the x87 FPU as well as state specific to SSE.
+  //!
+  //! As the `fsave` format is a subset of the `fxsave` format, this operation
+  //! cannot fully populate the `fxsave` area. Fields in \a fxsave that have no
+  //! equivalent in \a fsave are set to `0`, including Fxsave::mxcsr,
+  //! Fxsave::mxcsr_mask, Fxsave::xmm, and Fxsave::available.
+  //! FsaveToFxsaveTagWord() is used to derive Fxsave::ftw from the full 16-bit
+  //! form used by `fsave`. Reserved fields in \a fxsave are set to `0`.
+  //!
+  //! \param[in] fsave The `fsave` area to convert.
+  //! \param[out] fxsave The `fxsave` area to populate.
+  //!
+  //! \sa FxsaveToFsave()
+  static void FsaveToFxsave(const Fsave& fsave, Fxsave* fxsave);
+
   //! \brief Converts x87 floating-point tag words from `fxsave` (abridged,
   //!     8-bit) to `fsave` (full, 16-bit) form.
   //!
   //! `fxsave` stores the x87 floating-point tag word in abridged 8-bit form,
   //! and `fsave` stores it in full 16-bit form. Some users, notably
-  //! MinidumpContextX86::float_save::tag_word, require the full 16-bit form,
-  //! where most other contemporary code uses `fxsave` and thus the abridged
-  //! 8-bit form found in CPUContextX86::Fxsave::ftw.
+  //! CPUContextX86::Fsave::ftw, require the full 16-bit form, where most other
+  //! contemporary code uses `fxsave` and thus the abridged 8-bit form found in
+  //! CPUContextX86::Fxsave::ftw.
   //!
   //! This function converts an abridged tag word to the full version by using
   //! the abridged tag word and the contents of the registers it describes. See
@@ -75,6 +126,8 @@ struct CPUContextX86 {
   //! Manual, Volume 2: System Programming (24593-3.24), “FXSAVE Format for x87
   //! Tag Word”.
   //!
+  //! \sa FsaveToFxsaveTagWord()
+  //!
   //! \param[in] fsw The FPU status word, used to map logical \a st_mm registers
   //!     to their physical counterparts. This can be taken from
   //!     CPUContextX86::Fxsave::fsw.
@@ -87,6 +140,16 @@ struct CPUContextX86 {
   static uint16_t FxsaveToFsaveTagWord(
       uint16_t fsw, uint8_t fxsave_tag, const X87OrMMXRegister st_mm[8]);
 
+  //! \brief Converts x87 floating-point tag words from `fsave` (full, 16-bit)
+  //!     to `fxsave` (abridged, 8-bit) form.
+  //!
+  //! This function performs the inverse operation of FxsaveToFsaveTagWord().
+  //!
+  //! \param[in] fsave_tag The full FPU tag word.
+  //!
+  //! \return The abridged FPU tag word.
+  static uint8_t FsaveToFxsaveTagWord(uint16_t fsave_tag);
+
   // Integer registers.
   uint32_t eax;
   uint32_t ebx;
diff --git a/snapshot/cpu_context_test.cc b/snapshot/cpu_context_test.cc
index 808ba615..ffc18cfe 100644
--- a/snapshot/cpu_context_test.cc
+++ b/snapshot/cpu_context_test.cc
@@ -19,6 +19,7 @@
 
 #include "base/macros.h"
 #include "gtest/gtest.h"
+#include "test/hex_string.h"
 
 namespace crashpad {
 namespace test {
@@ -48,37 +49,188 @@ enum FractionValue {
 //! \param[in] j_bit The value to use for the “J bit” (“integer bit”).
 //! \param[in] fraction_value If kFractionAllZero, the fraction will be zeroed
 //!     out. If kFractionNormal, the fraction will not be all zeroes.
-void SetX87Register(CPUContextX86::X87OrMMXRegister* st_mm,
+void SetX87Register(CPUContextX86::X87Register* st,
                     ExponentValue exponent_value,
                     bool j_bit,
                     FractionValue fraction_value) {
   switch (exponent_value) {
     case kExponentAllZero:
-      st_mm->st[9] = 0x80;
-      st_mm->st[8] = 0;
+      (*st)[9] = 0x80;
+      (*st)[8] = 0;
       break;
     case kExponentAllOne:
-      st_mm->st[9] = 0x7f;
-      st_mm->st[8] = 0xff;
+      (*st)[9] = 0x7f;
+      (*st)[8] = 0xff;
       break;
     case kExponentNormal:
-      st_mm->st[9] = 0x55;
-      st_mm->st[8] = 0x55;
+      (*st)[9] = 0x55;
+      (*st)[8] = 0x55;
       break;
   }
 
   uint8_t fraction_pattern = fraction_value == kFractionAllZero ? 0 : 0x55;
-  memset(&st_mm->st[0], fraction_pattern, 8);
+  memset(st, fraction_pattern, 8);
 
   if (j_bit) {
-    st_mm->st[7] |= 0x80;
+    (*st)[7] |= 0x80;
   } else {
-    st_mm->st[7] &= ~0x80;
+    (*st)[7] &= ~0x80;
   }
+}
 
+//! \brief Initializes an x87 register to a known bit pattern.
+//!
+//! This behaves as SetX87Register() but also clears the reserved portion of the
+//! field as used in the `fxsave` format.
+void SetX87OrMMXRegister(CPUContextX86::X87OrMMXRegister* st_mm,
+                         ExponentValue exponent_value,
+                         bool j_bit,
+                         FractionValue fraction_value) {
+  SetX87Register(&st_mm->st, exponent_value, j_bit, fraction_value);
   memset(st_mm->st_reserved, 0, sizeof(st_mm->st_reserved));
 }
 
+TEST(CPUContextX86, FxsaveToFsave) {
+  // Establish a somewhat plausible fxsave state. Use nonzero values for
+  // reserved fields and things that aren’t present in fsave.
+  CPUContextX86::Fxsave fxsave;
+  fxsave.fcw = 0x027f;  // mask exceptions, 53-bit precision, round to nearest
+  fxsave.fsw = 1 << 11;  // top = 1: logical 0-7 maps to physical 1-7, 0
+  fxsave.ftw = 0x1f;  // physical 5-7 (logical 4-6) empty
+  fxsave.reserved_1 = 0x5a;
+  fxsave.fop = 0x1fe;  // fsin
+  fxsave.fpu_ip = 0x76543210;
+  fxsave.fpu_cs = 0x0007;
+  fxsave.reserved_2 = 0x5a5a;
+  fxsave.fpu_dp = 0xfedcba98;
+  fxsave.fpu_ds = 0x000f;
+  fxsave.reserved_3 = 0x5a5a;
+  fxsave.mxcsr = 0x1f80;
+  fxsave.mxcsr_mask = 0xffff;
+  SetX87Register(
+      &fxsave.st_mm[0].st, kExponentNormal, true, kFractionAllZero);  // valid
+  SetX87Register(
+      &fxsave.st_mm[1].st, kExponentAllZero, false, kFractionAllZero);  // zero
+  SetX87Register(
+      &fxsave.st_mm[2].st, kExponentAllOne, true, kFractionAllZero);  // spec.
+  SetX87Register(
+      &fxsave.st_mm[3].st, kExponentAllOne, true, kFractionNormal);  // spec.
+  SetX87Register(
+      &fxsave.st_mm[4].st, kExponentAllZero, false, kFractionAllZero);
+  SetX87Register(
+      &fxsave.st_mm[5].st, kExponentAllZero, false, kFractionAllZero);
+  SetX87Register(
+      &fxsave.st_mm[6].st, kExponentAllZero, false, kFractionAllZero);
+  SetX87Register(
+      &fxsave.st_mm[7].st, kExponentNormal, true, kFractionNormal);  // valid
+  for (size_t index = 0; index < arraysize(fxsave.st_mm); ++index) {
+    memset(&fxsave.st_mm[index].st_reserved,
+           0x5a,
+           sizeof(fxsave.st_mm[index].st_reserved));
+  }
+  memset(&fxsave.xmm, 0x5a, sizeof(fxsave) - offsetof(decltype(fxsave), xmm));
+
+  CPUContextX86::Fsave fsave;
+  CPUContextX86::FxsaveToFsave(fxsave, &fsave);
+
+  // Everything should have come over from fxsave. Reserved fields should be
+  // zero.
+  EXPECT_EQ(fxsave.fcw, fsave.fcw);
+  EXPECT_EQ(0, fsave.reserved_1);
+  EXPECT_EQ(fxsave.fsw, fsave.fsw);
+  EXPECT_EQ(0, fsave.reserved_2);
+  EXPECT_EQ(0xfe90, fsave.ftw);  // FxsaveToFsaveTagWord
+  EXPECT_EQ(0, fsave.reserved_3);
+  EXPECT_EQ(fxsave.fpu_ip, fsave.fpu_ip);
+  EXPECT_EQ(fxsave.fpu_cs, fsave.fpu_cs);
+  EXPECT_EQ(fxsave.fop, fsave.fop);
+  EXPECT_EQ(fxsave.fpu_dp, fsave.fpu_dp);
+  EXPECT_EQ(fxsave.fpu_ds, fsave.fpu_ds);
+  EXPECT_EQ(0, fsave.reserved_4);
+  for (size_t index = 0; index < arraysize(fsave.st); ++index) {
+    EXPECT_EQ(BytesToHexString(fxsave.st_mm[index].st,
+                               arraysize(fxsave.st_mm[index].st)),
+              BytesToHexString(fsave.st[index], arraysize(fsave.st[index])))
+        << "index " << index;
+  }
+}
+
+TEST(CPUContextX86, FsaveToFxsave) {
+  // Establish a somewhat plausible fsave state. Use nonzero values for
+  // reserved fields.
+  CPUContextX86::Fsave fsave;
+  fsave.fcw = 0x0300;  // unmask exceptions, 64-bit precision, round to nearest
+  fsave.reserved_1 = 0xa5a5;
+  fsave.fsw = 2 << 11;  // top = 2: logical 0-7 maps to physical 2-7, 0-1
+  fsave.reserved_2 = 0xa5a5;
+  fsave.ftw = 0xa9ff;  // physical 0-3 (logical 6-7, 0-1) empty; physical 4
+                       // (logical 2) zero; physical 5-7 (logical 3-5) special
+  fsave.reserved_3 = 0xa5a5;
+  fsave.fpu_ip = 0x456789ab;
+  fsave.fpu_cs = 0x1013;
+  fsave.fop = 0x01ee;  // fldz
+  fsave.fpu_dp = 0x0123cdef;
+  fsave.fpu_ds = 0x2017;
+  fsave.reserved_4 = 0xa5a5;
+  SetX87Register(&fsave.st[0], kExponentAllZero, false, kFractionNormal);
+  SetX87Register(&fsave.st[1], kExponentAllZero, true, kFractionNormal);
+  SetX87Register(
+      &fsave.st[2], kExponentAllZero, false, kFractionAllZero);  // zero
+  SetX87Register(
+      &fsave.st[3], kExponentAllZero, true, kFractionAllZero);  // spec.
+  SetX87Register(
+      &fsave.st[4], kExponentAllZero, false, kFractionNormal);  // spec.
+  SetX87Register(
+      &fsave.st[5], kExponentAllZero, true, kFractionNormal);  // spec.
+  SetX87Register(&fsave.st[6], kExponentAllZero, false, kFractionAllZero);
+  SetX87Register(&fsave.st[7], kExponentAllZero, true, kFractionAllZero);
+
+  CPUContextX86::Fxsave fxsave;
+  CPUContextX86::FsaveToFxsave(fsave, &fxsave);
+
+  // Everything in fsave should have come over from there. Fields not present in
+  // fsave and reserved fields should be zero.
+  EXPECT_EQ(fsave.fcw, fxsave.fcw);
+  EXPECT_EQ(fsave.fsw, fxsave.fsw);
+  EXPECT_EQ(0xf0, fxsave.ftw);  // FsaveToFxsaveTagWord
+  EXPECT_EQ(0, fxsave.reserved_1);
+  EXPECT_EQ(fsave.fop, fxsave.fop);
+  EXPECT_EQ(fsave.fpu_ip, fxsave.fpu_ip);
+  EXPECT_EQ(fsave.fpu_cs, fxsave.fpu_cs);
+  EXPECT_EQ(0, fxsave.reserved_2);
+  EXPECT_EQ(fsave.fpu_dp, fxsave.fpu_dp);
+  EXPECT_EQ(fsave.fpu_ds, fxsave.fpu_ds);
+  EXPECT_EQ(0, fxsave.reserved_3);
+  EXPECT_EQ(0u, fxsave.mxcsr);
+  EXPECT_EQ(0u, fxsave.mxcsr_mask);
+  for (size_t index = 0; index < arraysize(fxsave.st_mm); ++index) {
+    EXPECT_EQ(BytesToHexString(fsave.st[index], arraysize(fsave.st[index])),
+              BytesToHexString(fxsave.st_mm[index].st,
+                               arraysize(fxsave.st_mm[index].st)))
+        << "index " << index;
+    EXPECT_EQ(std::string(arraysize(fxsave.st_mm[index].st_reserved) * 2, '0'),
+              BytesToHexString(fxsave.st_mm[index].st_reserved,
+                               arraysize(fxsave.st_mm[index].st_reserved)))
+        << "index " << index;
+  }
+  size_t unused_len = sizeof(fxsave) - offsetof(decltype(fxsave), xmm);
+  EXPECT_EQ(std::string(unused_len * 2, '0'),
+            BytesToHexString(fxsave.xmm, unused_len));
+
+  // Since the fsave format is a subset of the fxsave format, fsave-fxsave-fsave
+  // should round-trip cleanly.
+  CPUContextX86::Fsave fsave_2;
+  CPUContextX86::FxsaveToFsave(fxsave, &fsave_2);
+
+  // Clear the reserved fields in the original fsave structure, since they’re
+  // expected to be clear in the copy.
+  fsave.reserved_1 = 0;
+  fsave.reserved_2 = 0;
+  fsave.reserved_3 = 0;
+  fsave.reserved_4 = 0;
+  EXPECT_EQ(0, memcmp(&fsave, &fsave_2, sizeof(fsave)));
+}
+
 TEST(CPUContextX86, FxsaveToFsaveTagWord) {
   // The fsave tag word uses bit pattern 00 for valid, 01 for zero, 10 for
   // “special”, and 11 for empty. Like the fxsave tag word, it is arranged by
@@ -93,40 +245,52 @@ TEST(CPUContextX86, FxsaveToFsaveTagWord) {
   uint16_t fsw = 0 << 11;  // top = 0: logical 0-7 maps to physical 0-7
   uint8_t fxsave_tag = 0x0f;  // physical 4-7 (logical 4-7) empty
   CPUContextX86::X87OrMMXRegister st_mm[8];
-  SetX87Register(&st_mm[0], kExponentNormal, false, kFractionNormal);  // spec.
-  SetX87Register(&st_mm[1], kExponentNormal, true, kFractionNormal);  // valid
-  SetX87Register(&st_mm[2], kExponentNormal, false, kFractionAllZero);  // spec.
-  SetX87Register(&st_mm[3], kExponentNormal, true, kFractionAllZero);  // valid
-  SetX87Register(&st_mm[4], kExponentNormal, false, kFractionNormal);
-  SetX87Register(&st_mm[5], kExponentNormal, true, kFractionNormal);
-  SetX87Register(&st_mm[6], kExponentNormal, false, kFractionAllZero);
-  SetX87Register(&st_mm[7], kExponentNormal, true, kFractionAllZero);
+  SetX87OrMMXRegister(
+      &st_mm[0], kExponentNormal, false, kFractionNormal);  // spec.
+  SetX87OrMMXRegister(
+      &st_mm[1], kExponentNormal, true, kFractionNormal);  // valid
+  SetX87OrMMXRegister(
+      &st_mm[2], kExponentNormal, false, kFractionAllZero);  // spec.
+  SetX87OrMMXRegister(
+      &st_mm[3], kExponentNormal, true, kFractionAllZero);  // valid
+  SetX87OrMMXRegister(&st_mm[4], kExponentNormal, false, kFractionNormal);
+  SetX87OrMMXRegister(&st_mm[5], kExponentNormal, true, kFractionNormal);
+  SetX87OrMMXRegister(&st_mm[6], kExponentNormal, false, kFractionAllZero);
+  SetX87OrMMXRegister(&st_mm[7], kExponentNormal, true, kFractionAllZero);
   EXPECT_EQ(0xff22,
             CPUContextX86::FxsaveToFsaveTagWord(fsw, fxsave_tag, st_mm));
 
   fsw = 2 << 11;  // top = 2: logical 0-7 maps to physical 2-7, 0-1
   fxsave_tag = 0xf0;  // physical 0-3 (logical 6-7, 0-1) empty
-  SetX87Register(&st_mm[0], kExponentAllZero, false, kFractionNormal);
-  SetX87Register(&st_mm[1], kExponentAllZero, true, kFractionNormal);
-  SetX87Register(&st_mm[2], kExponentAllZero, false, kFractionAllZero);  // zero
-  SetX87Register(&st_mm[3], kExponentAllZero, true, kFractionAllZero);  // spec.
-  SetX87Register(&st_mm[4], kExponentAllZero, false, kFractionNormal);  // spec.
-  SetX87Register(&st_mm[5], kExponentAllZero, true, kFractionNormal);  // spec.
-  SetX87Register(&st_mm[6], kExponentAllZero, false, kFractionAllZero);
-  SetX87Register(&st_mm[7], kExponentAllZero, true, kFractionAllZero);
+  SetX87OrMMXRegister(&st_mm[0], kExponentAllZero, false, kFractionNormal);
+  SetX87OrMMXRegister(&st_mm[1], kExponentAllZero, true, kFractionNormal);
+  SetX87OrMMXRegister(
+      &st_mm[2], kExponentAllZero, false, kFractionAllZero);  // zero
+  SetX87OrMMXRegister(
+      &st_mm[3], kExponentAllZero, true, kFractionAllZero);  // spec.
+  SetX87OrMMXRegister(
+      &st_mm[4], kExponentAllZero, false, kFractionNormal);  // spec.
+  SetX87OrMMXRegister(
+      &st_mm[5], kExponentAllZero, true, kFractionNormal);  // spec.
+  SetX87OrMMXRegister(&st_mm[6], kExponentAllZero, false, kFractionAllZero);
+  SetX87OrMMXRegister(&st_mm[7], kExponentAllZero, true, kFractionAllZero);
   EXPECT_EQ(0xa9ff,
             CPUContextX86::FxsaveToFsaveTagWord(fsw, fxsave_tag, st_mm));
 
   fsw = 5 << 11;  // top = 5: logical 0-7 maps to physical 5-7, 0-4
   fxsave_tag = 0x5a;  // physical 0, 2, 5, and 7 (logical 5, 0, 2, and 3) empty
-  SetX87Register(&st_mm[0], kExponentAllOne, false, kFractionNormal);
-  SetX87Register(&st_mm[1], kExponentAllOne, true, kFractionNormal);  // spec.
-  SetX87Register(&st_mm[2], kExponentAllOne, false, kFractionAllZero);
-  SetX87Register(&st_mm[3], kExponentAllOne, true, kFractionAllZero);
-  SetX87Register(&st_mm[4], kExponentAllOne, false, kFractionNormal);  // spec.
-  SetX87Register(&st_mm[5], kExponentAllOne, true, kFractionNormal);
-  SetX87Register(&st_mm[6], kExponentAllOne, false, kFractionAllZero);  // spec.
-  SetX87Register(&st_mm[7], kExponentAllOne, true, kFractionAllZero);  // spec.
+  SetX87OrMMXRegister(&st_mm[0], kExponentAllOne, false, kFractionNormal);
+  SetX87OrMMXRegister(
+      &st_mm[1], kExponentAllOne, true, kFractionNormal);  // spec.
+  SetX87OrMMXRegister(&st_mm[2], kExponentAllOne, false, kFractionAllZero);
+  SetX87OrMMXRegister(&st_mm[3], kExponentAllOne, true, kFractionAllZero);
+  SetX87OrMMXRegister(
+      &st_mm[4], kExponentAllOne, false, kFractionNormal);  // spec.
+  SetX87OrMMXRegister(&st_mm[5], kExponentAllOne, true, kFractionNormal);
+  SetX87OrMMXRegister(
+      &st_mm[6], kExponentAllOne, false, kFractionAllZero);  // spec.
+  SetX87OrMMXRegister(
+      &st_mm[7], kExponentAllOne, true, kFractionAllZero);  // spec.
   EXPECT_EQ(0xeebb,
             CPUContextX86::FxsaveToFsaveTagWord(fsw, fxsave_tag, st_mm));
 
@@ -134,14 +298,19 @@ TEST(CPUContextX86, FxsaveToFsaveTagWord) {
   // register file.
   fsw = 1 << 11;  // top = 1: logical 0-7 maps to physical 1-7, 0
   fxsave_tag = 0x1f;  // physical 5-7 (logical 4-6) empty
-  SetX87Register(&st_mm[0], kExponentNormal, true, kFractionAllZero);  // valid
-  SetX87Register(&st_mm[1], kExponentAllZero, false, kFractionAllZero);  // zero
-  SetX87Register(&st_mm[2], kExponentAllOne, true, kFractionAllZero);  // spec.
-  SetX87Register(&st_mm[3], kExponentAllOne, true, kFractionNormal);  // spec.
-  SetX87Register(&st_mm[4], kExponentAllZero, false, kFractionAllZero);
-  SetX87Register(&st_mm[5], kExponentAllZero, false, kFractionAllZero);
-  SetX87Register(&st_mm[6], kExponentAllZero, false, kFractionAllZero);
-  SetX87Register(&st_mm[7], kExponentNormal, true, kFractionNormal);  // valid
+  SetX87OrMMXRegister(
+      &st_mm[0], kExponentNormal, true, kFractionAllZero);  // valid
+  SetX87OrMMXRegister(
+      &st_mm[1], kExponentAllZero, false, kFractionAllZero);  // zero
+  SetX87OrMMXRegister(
+      &st_mm[2], kExponentAllOne, true, kFractionAllZero);  // spec.
+  SetX87OrMMXRegister(
+      &st_mm[3], kExponentAllOne, true, kFractionNormal);  // spec.
+  SetX87OrMMXRegister(&st_mm[4], kExponentAllZero, false, kFractionAllZero);
+  SetX87OrMMXRegister(&st_mm[5], kExponentAllZero, false, kFractionAllZero);
+  SetX87OrMMXRegister(&st_mm[6], kExponentAllZero, false, kFractionAllZero);
+  SetX87OrMMXRegister(
+      &st_mm[7], kExponentNormal, true, kFractionNormal);  // valid
   EXPECT_EQ(0xfe90,
             CPUContextX86::FxsaveToFsaveTagWord(fsw, fxsave_tag, st_mm));
 
@@ -149,7 +318,7 @@ TEST(CPUContextX86, FxsaveToFsaveTagWord) {
   fsw = 0 << 11;  // top = 0: logical 0-7 maps to physical 0-7
   fxsave_tag = 0xff;  // nothing empty
   for (size_t index = 0; index < arraysize(st_mm); ++index) {
-    SetX87Register(&st_mm[index], kExponentNormal, true, kFractionAllZero);
+    SetX87OrMMXRegister(&st_mm[index], kExponentNormal, true, kFractionAllZero);
   }
   EXPECT_EQ(0, CPUContextX86::FxsaveToFsaveTagWord(fsw, fxsave_tag, st_mm));
 
@@ -161,6 +330,17 @@ TEST(CPUContextX86, FxsaveToFsaveTagWord) {
             CPUContextX86::FxsaveToFsaveTagWord(fsw, fxsave_tag, st_mm));
 }
 
+TEST(CPUContextX86, FsaveToFxsaveTagWord) {
+  // The register sets that these x87 tag words might apply to are given in the
+  // FxsaveToFsaveTagWord test above.
+  EXPECT_EQ(0x0f, CPUContextX86::FsaveToFxsaveTagWord(0xff22));
+  EXPECT_EQ(0xf0, CPUContextX86::FsaveToFxsaveTagWord(0xa9ff));
+  EXPECT_EQ(0x5a, CPUContextX86::FsaveToFxsaveTagWord(0xeebb));
+  EXPECT_EQ(0x1f, CPUContextX86::FsaveToFxsaveTagWord(0xfe90));
+  EXPECT_EQ(0xff, CPUContextX86::FsaveToFxsaveTagWord(0x0000));
+  EXPECT_EQ(0x00, CPUContextX86::FsaveToFxsaveTagWord(0xffff));
+}
+
 }  // namespace
 }  // namespace test
 }  // namespace crashpad
diff --git a/snapshot/win/cpu_context_win.cc b/snapshot/win/cpu_context_win.cc
index 2450ef25..cc66e1cb 100644
--- a/snapshot/win/cpu_context_win.cc
+++ b/snapshot/win/cpu_context_win.cc
@@ -24,16 +24,53 @@ namespace crashpad {
 
 namespace {
 
+// Validation for casts used with CPUContextX86::FsaveToFxsave().
+static_assert(sizeof(CPUContextX86::Fsave) ==
+                  offsetof(WOW64_FLOATING_SAVE_AREA, Cr0NpxState),
+              "WoW64 fsave types must be equivalent");
+#if defined(ARCH_CPU_X86)
+static_assert(sizeof(CPUContextX86::Fsave) ==
+                  offsetof(FLOATING_SAVE_AREA, Spare0),
+              "fsave types must be equivalent");
+#endif  // ARCH_CPU_X86
+
+template <typename T>
+bool HasContextPart(const T& context, uint32_t bits) {
+  return (context.ContextFlags & bits) == bits;
+}
+
 template <class T>
 void CommonInitializeX86Context(const T& context, CPUContextX86* out) {
-  LOG_IF(ERROR, !(context.ContextFlags & WOW64_CONTEXT_i386))
-      << "non-x86 context";
+  // This function assumes that the WOW64_CONTEXT_* and x86 CONTEXT_* values
+  // for ContextFlags are identical. This can be tested when targeting 32-bit
+  // x86.
+#if defined(ARCH_CPU_X86)
+  static_assert(sizeof(CONTEXT) == sizeof(WOW64_CONTEXT),
+                "type mismatch: CONTEXT");
+#define ASSERT_WOW64_EQUIVALENT(x)                        \
+  do {                                                    \
+    static_assert(x == WOW64_##x, "value mismatch: " #x); \
+  } while (false)
+  ASSERT_WOW64_EQUIVALENT(CONTEXT_i386);
+  ASSERT_WOW64_EQUIVALENT(CONTEXT_i486);
+  ASSERT_WOW64_EQUIVALENT(CONTEXT_CONTROL);
+  ASSERT_WOW64_EQUIVALENT(CONTEXT_INTEGER);
+  ASSERT_WOW64_EQUIVALENT(CONTEXT_SEGMENTS);
+  ASSERT_WOW64_EQUIVALENT(CONTEXT_FLOATING_POINT);
+  ASSERT_WOW64_EQUIVALENT(CONTEXT_DEBUG_REGISTERS);
+  ASSERT_WOW64_EQUIVALENT(CONTEXT_EXTENDED_REGISTERS);
+  ASSERT_WOW64_EQUIVALENT(CONTEXT_FULL);
+  ASSERT_WOW64_EQUIVALENT(CONTEXT_ALL);
+  ASSERT_WOW64_EQUIVALENT(CONTEXT_XSTATE);
+#undef ASSERT_WOW64_EQUIVALENT
+#endif  // ARCH_CPU_X86
+
   memset(out, 0, sizeof(*out));
 
-  // We assume in this function that the WOW64_CONTEXT_* and x86 CONTEXT_*
-  // values for ContextFlags are identical.
+  LOG_IF(ERROR, !HasContextPart(context, WOW64_CONTEXT_i386))
+      << "non-x86 context";
 
-  if (context.ContextFlags & WOW64_CONTEXT_CONTROL) {
+  if (HasContextPart(context, WOW64_CONTEXT_CONTROL)) {
     out->ebp = context.Ebp;
     out->eip = context.Eip;
     out->cs = static_cast<uint16_t>(context.SegCs);
@@ -42,7 +79,7 @@ void CommonInitializeX86Context(const T& context, CPUContextX86* out) {
     out->ss = static_cast<uint16_t>(context.SegSs);
   }
 
-  if (context.ContextFlags & WOW64_CONTEXT_INTEGER) {
+  if (HasContextPart(context, WOW64_CONTEXT_INTEGER)) {
     out->eax = context.Eax;
     out->ebx = context.Ebx;
     out->ecx = context.Ecx;
@@ -51,32 +88,38 @@ void CommonInitializeX86Context(const T& context, CPUContextX86* out) {
     out->esi = context.Esi;
   }
 
-  if (context.ContextFlags & WOW64_CONTEXT_SEGMENTS) {
+  if (HasContextPart(context, WOW64_CONTEXT_SEGMENTS)) {
     out->ds = static_cast<uint16_t>(context.SegDs);
     out->es = static_cast<uint16_t>(context.SegEs);
     out->fs = static_cast<uint16_t>(context.SegFs);
     out->gs = static_cast<uint16_t>(context.SegGs);
   }
 
-  if (context.ContextFlags & WOW64_CONTEXT_DEBUG_REGISTERS) {
+  if (HasContextPart(context, WOW64_CONTEXT_DEBUG_REGISTERS)) {
     out->dr0 = context.Dr0;
     out->dr1 = context.Dr1;
     out->dr2 = context.Dr2;
     out->dr3 = context.Dr3;
+
     // DR4 and DR5 are obsolete synonyms for DR6 and DR7, see
     // https://en.wikipedia.org/wiki/X86_debug_register.
     out->dr4 = context.Dr6;
     out->dr5 = context.Dr7;
+
     out->dr6 = context.Dr6;
     out->dr7 = context.Dr7;
   }
 
-  if (context.ContextFlags & WOW64_CONTEXT_EXTENDED_REGISTERS) {
+  if (HasContextPart(context, WOW64_CONTEXT_EXTENDED_REGISTERS)) {
     static_assert(sizeof(out->fxsave) == sizeof(context.ExtendedRegisters),
-                  "types must be equivalent");
+                  "fxsave types must be equivalent");
     memcpy(&out->fxsave, &context.ExtendedRegisters, sizeof(out->fxsave));
-  } else if (context.ContextFlags & WOW64_CONTEXT_FLOATING_POINT) {
-    CHECK(false) << "TODO(scottmg): extract x87 data";
+  } else if (HasContextPart(context, WOW64_CONTEXT_FLOATING_POINT)) {
+    // The static_assert that validates this cast can’t be here because it
+    // relies on field names that vary based on the template parameter.
+    CPUContextX86::FsaveToFxsave(
+        *reinterpret_cast<const CPUContextX86::Fsave*>(&context.FloatSave),
+        &out->fxsave);
   }
 }
 
@@ -91,9 +134,9 @@ void InitializeX86Context(const WOW64_CONTEXT& context, CPUContextX86* out) {
 void InitializeX64Context(const CONTEXT& context, CPUContextX86_64* out) {
   memset(out, 0, sizeof(*out));
 
-  LOG_IF(ERROR, !(context.ContextFlags & CONTEXT_AMD64)) << "non-x64 context";
+  LOG_IF(ERROR, !HasContextPart(context, CONTEXT_AMD64)) << "non-x64 context";
 
-  if (context.ContextFlags & CONTEXT_CONTROL) {
+  if (HasContextPart(context, CONTEXT_CONTROL)) {
     out->cs = context.SegCs;
     out->rflags = context.EFlags;
     out->rip = context.Rip;
@@ -101,7 +144,7 @@ void InitializeX64Context(const CONTEXT& context, CPUContextX86_64* out) {
     // SegSs ignored.
   }
 
-  if (context.ContextFlags & CONTEXT_INTEGER) {
+  if (HasContextPart(context, CONTEXT_INTEGER)) {
     out->rax = context.Rax;
     out->rbx = context.Rbx;
     out->rcx = context.Rcx;
@@ -119,30 +162,32 @@ void InitializeX64Context(const CONTEXT& context, CPUContextX86_64* out) {
     out->r15 = context.R15;
   }
 
-  if (context.ContextFlags & CONTEXT_SEGMENTS) {
+  if (HasContextPart(context, CONTEXT_SEGMENTS)) {
     out->fs = context.SegFs;
     out->gs = context.SegGs;
     // SegDs ignored.
     // SegEs ignored.
   }
 
-  if (context.ContextFlags & CONTEXT_DEBUG_REGISTERS) {
+  if (HasContextPart(context, CONTEXT_DEBUG_REGISTERS)) {
     out->dr0 = context.Dr0;
     out->dr1 = context.Dr1;
     out->dr2 = context.Dr2;
     out->dr3 = context.Dr3;
+
     // DR4 and DR5 are obsolete synonyms for DR6 and DR7, see
     // https://en.wikipedia.org/wiki/X86_debug_register.
     out->dr4 = context.Dr6;
     out->dr5 = context.Dr7;
+
     out->dr6 = context.Dr6;
     out->dr7 = context.Dr7;
   }
 
-  if (context.ContextFlags & CONTEXT_FLOATING_POINT) {
+  if (HasContextPart(context, CONTEXT_FLOATING_POINT)) {
     static_assert(sizeof(out->fxsave) == sizeof(context.FltSave),
                   "types must be equivalent");
-    memcpy(&out->fxsave, &context.FltSave.ControlWord, sizeof(out->fxsave));
+    memcpy(&out->fxsave, &context.FltSave, sizeof(out->fxsave));
   }
 }
 
diff --git a/snapshot/win/cpu_context_win_test.cc b/snapshot/win/cpu_context_win_test.cc
index 0c7484b7..b2e6aae5 100644
--- a/snapshot/win/cpu_context_win_test.cc
+++ b/snapshot/win/cpu_context_win_test.cc
@@ -16,14 +16,92 @@
 
 #include <windows.h>
 
+#include "base/macros.h"
 #include "build/build_config.h"
 #include "gtest/gtest.h"
+#include "test/hex_string.h"
 #include "snapshot/cpu_context.h"
 
 namespace crashpad {
 namespace test {
 namespace {
 
+template <typename T>
+void TestInitializeX86Context() {
+  T context = {0};
+  context.ContextFlags = WOW64_CONTEXT_INTEGER |
+                         WOW64_CONTEXT_DEBUG_REGISTERS |
+                         WOW64_CONTEXT_EXTENDED_REGISTERS;
+  context.Eax = 1;
+  context.Dr0 = 3;
+  context.ExtendedRegisters[4] = 2;  // FTW
+
+  // Test the simple case, where everything in the CPUContextX86 argument is set
+  // directly from the supplied thread, float, and debug state parameters.
+  {
+    CPUContextX86 cpu_context_x86 = {};
+    InitializeX86Context(context, &cpu_context_x86);
+    EXPECT_EQ(1u, cpu_context_x86.eax);
+    EXPECT_EQ(2u, cpu_context_x86.fxsave.ftw);
+    EXPECT_EQ(3u, cpu_context_x86.dr0);
+  }
+}
+
+template <typename T>
+void TestInitializeX86Context_FsaveWithoutFxsave() {
+  T context = {0};
+  context.ContextFlags = WOW64_CONTEXT_INTEGER |
+                         WOW64_CONTEXT_FLOATING_POINT |
+                         WOW64_CONTEXT_DEBUG_REGISTERS;
+  context.Eax = 1;
+
+  // In fields that are wider than they need to be, set the high bits to ensure
+  // that they’re masked off appropriately in the output.
+  context.FloatSave.ControlWord = 0xffff027f;
+  context.FloatSave.StatusWord = 0xffff0004;
+  context.FloatSave.TagWord = 0xffffa9ff;
+  context.FloatSave.ErrorOffset = 0x01234567;
+  context.FloatSave.ErrorSelector = 0x0bad0003;
+  context.FloatSave.DataOffset = 0x89abcdef;
+  context.FloatSave.DataSelector = 0xffff0007;
+  context.FloatSave.RegisterArea[77] = 0x80;
+  context.FloatSave.RegisterArea[78] = 0xff;
+  context.FloatSave.RegisterArea[79] = 0x7f;
+
+  context.Dr0 = 3;
+
+  {
+    CPUContextX86 cpu_context_x86 = {};
+    InitializeX86Context(context, &cpu_context_x86);
+
+    EXPECT_EQ(1u, cpu_context_x86.eax);
+
+    EXPECT_EQ(0x027f, cpu_context_x86.fxsave.fcw);
+    EXPECT_EQ(0x0004, cpu_context_x86.fxsave.fsw);
+    EXPECT_EQ(0x00f0, cpu_context_x86.fxsave.ftw);
+    EXPECT_EQ(0x0bad, cpu_context_x86.fxsave.fop);
+    EXPECT_EQ(0x01234567, cpu_context_x86.fxsave.fpu_ip);
+    EXPECT_EQ(0x0003, cpu_context_x86.fxsave.fpu_cs);
+    EXPECT_EQ(0x89abcdef, cpu_context_x86.fxsave.fpu_dp);
+    EXPECT_EQ(0x0007, cpu_context_x86.fxsave.fpu_ds);
+    for (size_t st_mm = 0; st_mm < 7; ++st_mm) {
+      EXPECT_EQ(
+          std::string(arraysize(cpu_context_x86.fxsave.st_mm[st_mm].st) * 2,
+                      '0'),
+          BytesToHexString(cpu_context_x86.fxsave.st_mm[st_mm].st,
+                           arraysize(cpu_context_x86.fxsave.st_mm[st_mm].st)))
+          << "st_mm " << st_mm;
+    }
+    EXPECT_EQ("0000000000000080ff7f",
+              BytesToHexString(cpu_context_x86.fxsave.st_mm[7].st,
+                               arraysize(cpu_context_x86.fxsave.st_mm[7].st)));
+
+    EXPECT_EQ(3u, cpu_context_x86.dr0);
+  }
+}
+
+#if defined(ARCH_CPU_X86_FAMILY)
+
 #if defined(ARCH_CPU_X86_64)
 
 TEST(CPUContextWin, InitializeX64Context) {
@@ -45,28 +123,25 @@ TEST(CPUContextWin, InitializeX64Context) {
   }
 }
 
-#else
+#endif  // ARCH_CPU_X86_64
 
 TEST(CPUContextWin, InitializeX86Context) {
-  CONTEXT context = {0};
-  context.ContextFlags =
-      CONTEXT_INTEGER | CONTEXT_EXTENDED_REGISTERS | CONTEXT_DEBUG_REGISTERS;
-  context.Eax = 1;
-  context.ExtendedRegisters[4] = 2;  // FTW.
-  context.Dr0 = 3;
-
-  // Test the simple case, where everything in the CPUContextX86 argument is
-  // set directly from the supplied thread, float, and debug state parameters.
-  {
-    CPUContextX86 cpu_context_x86 = {};
-    InitializeX86Context(context, &cpu_context_x86);
-    EXPECT_EQ(1u, cpu_context_x86.eax);
-    EXPECT_EQ(2u, cpu_context_x86.fxsave.ftw);
-    EXPECT_EQ(3u, cpu_context_x86.dr0);
-  }
+#if defined(ARCH_CPU_X86)
+  TestInitializeX86Context<CONTEXT>();
+#else  // ARCH_CPU_X86
+  TestInitializeX86Context<WOW64_CONTEXT>();
+#endif  // ARCH_CPU_X86
 }
 
-#endif  // ARCH_CPU_X86_64
+TEST(CPUContextWin, InitializeX86Context_FsaveWithoutFxsave) {
+#if defined(ARCH_CPU_X86)
+  TestInitializeX86Context_FsaveWithoutFxsave<CONTEXT>();
+#else  // ARCH_CPU_X86
+  TestInitializeX86Context_FsaveWithoutFxsave<WOW64_CONTEXT>();
+#endif  // ARCH_CPU_X86
+}
+
+#endif  // ARCH_CPU_X86_FAMILY
 
 }  // namespace
 }  // namespace test
diff --git a/test/hex_string.cc b/test/hex_string.cc
new file mode 100644
index 00000000..bb9b5f3a
--- /dev/null
+++ b/test/hex_string.cc
@@ -0,0 +1,35 @@
+// Copyright 2017 The Crashpad Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "test/hex_string.h"
+
+#include "base/strings/stringprintf.h"
+
+namespace crashpad {
+namespace test {
+
+std::string BytesToHexString(const void* bytes, size_t length) {
+  const unsigned char* bytes_c = reinterpret_cast<const unsigned char*>(bytes);
+
+  std::string hex_string;
+  hex_string.reserve(length * 2);
+  for (size_t index = 0; index < length; ++index) {
+    hex_string.append(base::StringPrintf("%02x", bytes_c[index]));
+  }
+
+  return hex_string;
+}
+
+}  // namespace test
+}  // namespace crashpad
diff --git a/test/hex_string.h b/test/hex_string.h
new file mode 100644
index 00000000..08654880
--- /dev/null
+++ b/test/hex_string.h
@@ -0,0 +1,40 @@
+// Copyright 2017 The Crashpad Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef CRASHPAD_TEST_HEX_STRING_H_
+#define CRASHPAD_TEST_HEX_STRING_H_
+
+#include <sys/types.h>
+
+#include <string>
+
+namespace crashpad {
+namespace test {
+
+//! \brief Returns a hexadecimal string corresponding to \a bytes and \a length.
+//!
+//! Example usage:
+//! \code
+//!   uint8_t expected[10];
+//!   uint8_t observed[10];
+//!   // …
+//!   EXPECT_EQ(BytesToHexString(expected, arraysize(expected)),
+//!             BytesToHexString(observed, arraysize(observed)));
+//! \endcode
+std::string BytesToHexString(const void* bytes, size_t length);
+
+}  // namespace test
+}  // namespace crashpad
+
+#endif  // CRASHPAD_TEST_HEX_STRING_H_
diff --git a/test/hex_string_test.cc b/test/hex_string_test.cc
new file mode 100644
index 00000000..62b45c12
--- /dev/null
+++ b/test/hex_string_test.cc
@@ -0,0 +1,34 @@
+// Copyright 2017 The Crashpad Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "test/hex_string.h"
+
+#include "base/macros.h"
+#include "gtest/gtest.h"
+
+namespace crashpad {
+namespace test {
+namespace {
+
+TEST(HexString, HexString) {
+  EXPECT_EQ("", BytesToHexString(nullptr, 0));
+
+  const char kBytes[] = "Abc123xyz \x0a\x7f\xf0\x9f\x92\xa9_";
+  EXPECT_EQ("41626331323378797a200a7ff09f92a95f00",
+            BytesToHexString(kBytes, arraysize(kBytes)));
+}
+
+}  // namespace
+}  // namespace test
+}  // namespace crashpad
diff --git a/test/test.gyp b/test/test.gyp
index 666a68a1..d84ff640 100644
--- a/test/test.gyp
+++ b/test/test.gyp
@@ -35,6 +35,8 @@
         'file.cc',
         'file.h',
         'gtest_death_check.h',
+        'hex_string.cc',
+        'hex_string.h',
         'mac/dyld.h',
         'mac/mach_errors.cc',
         'mac/mach_errors.h',
diff --git a/test/test_test.gyp b/test/test_test.gyp
index e4405fcc..2c58c170 100644
--- a/test/test_test.gyp
+++ b/test/test_test.gyp
@@ -34,6 +34,7 @@
         '..',
       ],
       'sources': [
+        'hex_string_test.cc',
         'mac/mach_multiprocess_test.cc',
         'multiprocess_exec_test.cc',
         'multiprocess_posix_test.cc',
diff --git a/third_party/gtest/gmock.gyp b/third_party/gtest/gmock.gyp
index 683b89e1..466de6a9 100644
--- a/third_party/gtest/gmock.gyp
+++ b/third_party/gtest/gmock.gyp
@@ -17,212 +17,190 @@
     '../../build/crashpad_dependencies.gypi',
   ],
   'conditions': [
-    ['crashpad_dependencies!="chromium"', {
+    ['1==1', {  # Defer processing until crashpad_dependencies is set
       'variables': {
         'conditions': [
           ['crashpad_dependencies=="standalone"', {
             'gmock_dir': 'gtest/googlemock',
-          }, {
+          }],
+          ['crashpad_dependencies=="external"', {
             'gmock_dir': '../../../../gmock',
           }],
         ],
       },
-      'target_defaults': {
-        # gmock relies heavily on objects with static storage duration.
-        'xcode_settings': {
-          'WARNING_CFLAGS!': [
-            '-Wexit-time-destructors',
-          ],
-        },
-        'cflags!': [
-          '-Wexit-time-destructors',
+    }],
+  ],
+  'target_defaults': {
+    # gmock relies heavily on objects with static storage duration.
+    'xcode_settings': {
+      'WARNING_CFLAGS!': [
+        '-Wexit-time-destructors',
+      ],
+    },
+    'cflags!': [
+      '-Wexit-time-destructors',
+    ],
+  },
+
+  'targets': [
+    {
+      'target_name': 'gmock',
+      'type': 'static_library',
+      'dependencies': [
+        'gtest.gyp:gtest',
+      ],
+      'include_dirs': [
+        '<(gmock_dir)',
+        '<(gmock_dir)/include',
+      ],
+      'sources': [
+        '<(gmock_dir)/include/gmock/gmock-actions.h',
+        '<(gmock_dir)/include/gmock/gmock-cardinalities.h',
+        '<(gmock_dir)/include/gmock/gmock-generated-actions.h',
+        '<(gmock_dir)/include/gmock/gmock-generated-function-mockers.h',
+        '<(gmock_dir)/include/gmock/gmock-generated-matchers.h',
+        '<(gmock_dir)/include/gmock/gmock-generated-nice-strict.h',
+        '<(gmock_dir)/include/gmock/gmock-matchers.h',
+        '<(gmock_dir)/include/gmock/gmock-more-actions.h',
+        '<(gmock_dir)/include/gmock/gmock-more-matchers.h',
+        '<(gmock_dir)/include/gmock/gmock-spec-builders.h',
+        '<(gmock_dir)/include/gmock/gmock.h',
+        '<(gmock_dir)/include/gmock/internal/custom/gmock-generated-actions.h',
+        '<(gmock_dir)/include/gmock/internal/custom/gmock-matchers.h',
+        '<(gmock_dir)/include/gmock/internal/custom/gmock-port.h',
+        '<(gmock_dir)/include/gmock/internal/gmock-generated-internal-utils.h',
+        '<(gmock_dir)/include/gmock/internal/gmock-internal-utils.h',
+        '<(gmock_dir)/include/gmock/internal/gmock-port.h',
+        '<(gmock_dir)/src/gmock-all.cc',
+        '<(gmock_dir)/src/gmock-cardinalities.cc',
+        '<(gmock_dir)/src/gmock-internal-utils.cc',
+        '<(gmock_dir)/src/gmock-matchers.cc',
+        '<(gmock_dir)/src/gmock-spec-builders.cc',
+        '<(gmock_dir)/src/gmock.cc',
+      ],
+      'sources!': [
+        '<(gmock_dir)/src/gmock-all.cc',
+      ],
+
+      'direct_dependent_settings': {
+        'include_dirs': [
+          '<(gmock_dir)/include',
         ],
-      },
-
-      'targets': [
-        {
-          'target_name': 'gmock',
-          'type': 'static_library',
-          'dependencies': [
-            'gtest.gyp:gtest',
-          ],
-          'include_dirs': [
-            '<(gmock_dir)',
-            '<(gmock_dir)/include',
-          ],
-          'sources': [
-            '<(gmock_dir)/include/gmock/gmock-actions.h',
-            '<(gmock_dir)/include/gmock/gmock-cardinalities.h',
-            '<(gmock_dir)/include/gmock/gmock-generated-actions.h',
-            '<(gmock_dir)/include/gmock/gmock-generated-function-mockers.h',
-            '<(gmock_dir)/include/gmock/gmock-generated-matchers.h',
-            '<(gmock_dir)/include/gmock/gmock-generated-nice-strict.h',
-            '<(gmock_dir)/include/gmock/gmock-matchers.h',
-            '<(gmock_dir)/include/gmock/gmock-more-actions.h',
-            '<(gmock_dir)/include/gmock/gmock-more-matchers.h',
-            '<(gmock_dir)/include/gmock/gmock-spec-builders.h',
-            '<(gmock_dir)/include/gmock/gmock.h',
-            '<(gmock_dir)/include/gmock/internal/custom/gmock-generated-actions.h',
-            '<(gmock_dir)/include/gmock/internal/custom/gmock-matchers.h',
-            '<(gmock_dir)/include/gmock/internal/custom/gmock-port.h',
-            '<(gmock_dir)/include/gmock/internal/gmock-generated-internal-utils.h',
-            '<(gmock_dir)/include/gmock/internal/gmock-internal-utils.h',
-            '<(gmock_dir)/include/gmock/internal/gmock-port.h',
-            '<(gmock_dir)/src/gmock-all.cc',
-            '<(gmock_dir)/src/gmock-cardinalities.cc',
-            '<(gmock_dir)/src/gmock-internal-utils.cc',
-            '<(gmock_dir)/src/gmock-matchers.cc',
-            '<(gmock_dir)/src/gmock-spec-builders.cc',
-            '<(gmock_dir)/src/gmock.cc',
-          ],
-          'sources!': [
-            '<(gmock_dir)/src/gmock-all.cc',
-          ],
-
-          'direct_dependent_settings': {
-            'include_dirs': [
-              '<(gmock_dir)/include',
-            ],
+        'conditions': [
+          ['clang!=0', {
+            # The MOCK_METHODn() macros do not specify “override”, which
+            # triggers this warning in users: “error: 'Method' overrides a
+            # member function but is not marked 'override'
+            # [-Werror,-Winconsistent-missing-override]”. Suppress these
+            # warnings, and add -Wno-unknown-warning-option because only
+            # recent versions of clang (trunk r220703 and later, version
+            # 3.6 and later) recognize it.
             'conditions': [
-              ['clang!=0', {
-                # The MOCK_METHODn() macros do not specify “override”, which
-                # triggers this warning in users: “error: 'Method' overrides a
-                # member function but is not marked 'override'
-                # [-Werror,-Winconsistent-missing-override]”. Suppress these
-                # warnings, and add -Wno-unknown-warning-option because only
-                # recent versions of clang (trunk r220703 and later, version
-                # 3.6 and later) recognize it.
-                'conditions': [
-                  ['OS=="mac"', {
-                    'xcode_settings': {
-                      'WARNING_CFLAGS': [
-                        '-Wno-inconsistent-missing-override',
-                        '-Wno-unknown-warning-option',
-                      ],
-                    },
-                  }],
-                  ['OS=="linux"', {
-                    'cflags': [
-                      '-Wno-inconsistent-missing-override',
-                      '-Wno-unknown-warning-option',
-                    ],
-                  }],
+              ['OS=="mac"', {
+                'xcode_settings': {
+                  'WARNING_CFLAGS': [
+                    '-Wno-inconsistent-missing-override',
+                    '-Wno-unknown-warning-option',
+                  ],
+                },
+              }],
+              ['OS=="linux"', {
+                'cflags': [
+                  '-Wno-inconsistent-missing-override',
+                  '-Wno-unknown-warning-option',
                 ],
               }],
             ],
-          },
-          'export_dependent_settings': [
-            'gtest.gyp:gtest',
-          ],
-        },
-        {
-          'target_name': 'gmock_main',
-          'type': 'static_library',
-          'dependencies': [
-            'gmock',
-            'gtest.gyp:gtest',
-          ],
-          'sources': [
-            '<(gmock_dir)/src/gmock_main.cc',
-          ],
-        },
-        {
-          'target_name': 'gmock_test_executable',
-          'type': 'none',
-          'dependencies': [
-            'gmock',
-            'gtest.gyp:gtest',
-          ],
-          'direct_dependent_settings': {
-            'type': 'executable',
-            'include_dirs': [
-              '<(gmock_dir)',
-            ],
-          },
-          'export_dependent_settings': [
-            'gmock',
-            'gtest.gyp:gtest',
-          ],
-        },
-        {
-          'target_name': 'gmock_all_test',
-          'dependencies': [
-            'gmock_test_executable',
-            'gmock_main',
-          ],
-          'include_dirs': [
-            'gtest/googletest',
-          ],
-          'sources': [
-            '<(gmock_dir)/test/gmock-actions_test.cc',
-            '<(gmock_dir)/test/gmock-cardinalities_test.cc',
-            '<(gmock_dir)/test/gmock-generated-actions_test.cc',
-            '<(gmock_dir)/test/gmock-generated-function-mockers_test.cc',
-            '<(gmock_dir)/test/gmock-generated-internal-utils_test.cc',
-            '<(gmock_dir)/test/gmock-generated-matchers_test.cc',
-            '<(gmock_dir)/test/gmock-internal-utils_test.cc',
-            '<(gmock_dir)/test/gmock-matchers_test.cc',
-            '<(gmock_dir)/test/gmock-more-actions_test.cc',
-            '<(gmock_dir)/test/gmock-nice-strict_test.cc',
-            '<(gmock_dir)/test/gmock-port_test.cc',
-            '<(gmock_dir)/test/gmock-spec-builders_test.cc',
-            '<(gmock_dir)/test/gmock_test.cc',
-          ],
-        },
-        {
-          'target_name': 'gmock_link_test',
-          'dependencies': [
-            'gmock_test_executable',
-            'gmock_main',
-          ],
-          'sources': [
-            '<(gmock_dir)/test/gmock_link_test.cc',
-            '<(gmock_dir)/test/gmock_link_test.h',
-            '<(gmock_dir)/test/gmock_link2_test.cc',
-          ],
-        },
-        {
-          'target_name': 'gmock_stress_test',
-          'dependencies': [
-            'gmock_test_executable',
-          ],
-          'sources': [
-            '<(gmock_dir)/test/gmock_stress_test.cc',
-          ],
-        },
-        {
-          'target_name': 'gmock_all_tests',
-          'type': 'none',
-          'dependencies': [
-            'gmock_all_test',
-            'gmock_link_test',
-            'gmock_stress_test',
-          ],
-        },
+          }],
+        ],
+      },
+      'export_dependent_settings': [
+        'gtest.gyp:gtest',
       ],
-    }, {  # else: crashpad_dependencies=="chromium"
-      'targets': [
-        {
-          'target_name': 'gmock',
-          'type': 'none',
-          'dependencies': [
-            '<(DEPTH)/testing/gmock.gyp:gmock',
-          ],
-          'export_dependent_settings': [
-            '<(DEPTH)/testing/gmock.gyp:gmock',
-          ],
-        },
-        {
-          'target_name': 'gmock_main',
-          'type': 'none',
-          'dependencies': [
-            '<(DEPTH)/testing/gmock.gyp:gmock_main',
-          ],
-          'export_dependent_settings': [
-            '<(DEPTH)/testing/gmock.gyp:gmock_main',
-          ],
-        },
+    },
+    {
+      'target_name': 'gmock_main',
+      'type': 'static_library',
+      'dependencies': [
+        'gmock',
+        'gtest.gyp:gtest',
       ],
-    }],
+      'sources': [
+        '<(gmock_dir)/src/gmock_main.cc',
+      ],
+    },
+    {
+      'target_name': 'gmock_test_executable',
+      'type': 'none',
+      'dependencies': [
+        'gmock',
+        'gtest.gyp:gtest',
+      ],
+      'direct_dependent_settings': {
+        'type': 'executable',
+        'include_dirs': [
+          '<(gmock_dir)',
+        ],
+      },
+      'export_dependent_settings': [
+        'gmock',
+        'gtest.gyp:gtest',
+      ],
+    },
+    {
+      'target_name': 'gmock_all_test',
+      'dependencies': [
+        'gmock_test_executable',
+        'gmock_main',
+      ],
+      'include_dirs': [
+        'gtest/googletest',
+      ],
+      'sources': [
+        '<(gmock_dir)/test/gmock-actions_test.cc',
+        '<(gmock_dir)/test/gmock-cardinalities_test.cc',
+        '<(gmock_dir)/test/gmock-generated-actions_test.cc',
+        '<(gmock_dir)/test/gmock-generated-function-mockers_test.cc',
+        '<(gmock_dir)/test/gmock-generated-internal-utils_test.cc',
+        '<(gmock_dir)/test/gmock-generated-matchers_test.cc',
+        '<(gmock_dir)/test/gmock-internal-utils_test.cc',
+        '<(gmock_dir)/test/gmock-matchers_test.cc',
+        '<(gmock_dir)/test/gmock-more-actions_test.cc',
+        '<(gmock_dir)/test/gmock-nice-strict_test.cc',
+        '<(gmock_dir)/test/gmock-port_test.cc',
+        '<(gmock_dir)/test/gmock-spec-builders_test.cc',
+        '<(gmock_dir)/test/gmock_test.cc',
+      ],
+    },
+    {
+      'target_name': 'gmock_link_test',
+      'dependencies': [
+        'gmock_test_executable',
+        'gmock_main',
+      ],
+      'sources': [
+        '<(gmock_dir)/test/gmock_link_test.cc',
+        '<(gmock_dir)/test/gmock_link_test.h',
+        '<(gmock_dir)/test/gmock_link2_test.cc',
+      ],
+    },
+    {
+      'target_name': 'gmock_stress_test',
+      'dependencies': [
+        'gmock_test_executable',
+      ],
+      'sources': [
+        '<(gmock_dir)/test/gmock_stress_test.cc',
+      ],
+    },
+    {
+      'target_name': 'gmock_all_tests',
+      'type': 'none',
+      'dependencies': [
+        'gmock_all_test',
+        'gmock_link_test',
+        'gmock_stress_test',
+      ],
+    },
   ],
 }
diff --git a/third_party/gtest/gtest.gyp b/third_party/gtest/gtest.gyp
index e01adaf5..ad458936 100644
--- a/third_party/gtest/gtest.gyp
+++ b/third_party/gtest/gtest.gyp
@@ -17,274 +17,252 @@
     '../../build/crashpad_dependencies.gypi',
   ],
   'conditions': [
-    ['crashpad_dependencies!="chromium"', {
+    ['1==1', {  # Defer processing until crashpad_dependencies is set
       'variables': {
         'conditions': [
           ['crashpad_dependencies=="standalone"', {
             'gtest_dir': 'gtest/googletest',
-          }, {
+          }],
+          ['crashpad_dependencies=="external"', {
             'gtest_dir': '../../../../gtest',
           }],
         ],
       },
-      'target_defaults': {
-        # gtest relies heavily on objects with static storage duration.
-        'xcode_settings': {
-          'WARNING_CFLAGS!': [
-            '-Wexit-time-destructors',
-          ],
-        },
-        'cflags!': [
-          '-Wexit-time-destructors',
-        ],
-      },
-
-      'targets': [
-        {
-          'target_name': 'gtest',
-          'type': 'static_library',
-          'include_dirs': [
-            '<(gtest_dir)',
-            '<(gtest_dir)/include',
-          ],
-          'sources': [
-            '<(gtest_dir)/include/gtest/gtest-death-test.h',
-            '<(gtest_dir)/include/gtest/gtest-message.h',
-            '<(gtest_dir)/include/gtest/gtest-param-test.h',
-            '<(gtest_dir)/include/gtest/gtest-printers.h',
-            '<(gtest_dir)/include/gtest/gtest-spi.h',
-            '<(gtest_dir)/include/gtest/gtest-test-part.h',
-            '<(gtest_dir)/include/gtest/gtest-typed-test.h',
-            '<(gtest_dir)/include/gtest/gtest.h',
-            '<(gtest_dir)/include/gtest/gtest_pred_impl.h',
-            '<(gtest_dir)/include/gtest/gtest_prod.h',
-            '<(gtest_dir)/include/gtest/internal/custom/gtest-port.h',
-            '<(gtest_dir)/include/gtest/internal/custom/gtest-printers.h',
-            '<(gtest_dir)/include/gtest/internal/custom/gtest.h',
-            '<(gtest_dir)/include/gtest/internal/gtest-death-test-internal.h',
-            '<(gtest_dir)/include/gtest/internal/gtest-filepath.h',
-            '<(gtest_dir)/include/gtest/internal/gtest-internal.h',
-            '<(gtest_dir)/include/gtest/internal/gtest-linked_ptr.h',
-            '<(gtest_dir)/include/gtest/internal/gtest-param-util-generated.h',
-            '<(gtest_dir)/include/gtest/internal/gtest-param-util.h',
-            '<(gtest_dir)/include/gtest/internal/gtest-port-arch.h',
-            '<(gtest_dir)/include/gtest/internal/gtest-port.h',
-            '<(gtest_dir)/include/gtest/internal/gtest-string.h',
-            '<(gtest_dir)/include/gtest/internal/gtest-tuple.h',
-            '<(gtest_dir)/include/gtest/internal/gtest-type-util.h',
-            '<(gtest_dir)/src/gtest-all.cc',
-            '<(gtest_dir)/src/gtest-death-test.cc',
-            '<(gtest_dir)/src/gtest-filepath.cc',
-            '<(gtest_dir)/src/gtest-internal-inl.h',
-            '<(gtest_dir)/src/gtest-port.cc',
-            '<(gtest_dir)/src/gtest-printers.cc',
-            '<(gtest_dir)/src/gtest-test-part.cc',
-            '<(gtest_dir)/src/gtest-typed-test.cc',
-            '<(gtest_dir)/src/gtest.cc',
-          ],
-          'sources!': [
-            '<(gtest_dir)/src/gtest-all.cc',
-          ],
-          'direct_dependent_settings': {
-            'include_dirs': [
-              '<(gtest_dir)/include',
-            ],
-          },
-          'conditions': [
-            ['crashpad_dependencies=="external"', {
-              'include_dirs': [
-                '<(gtest_dir)/../..',
-              ],
-              'defines': [
-                'GUNIT_NO_GOOGLE3=1',
-              ],
-              'direct_dependent_settings': {
-                'include_dirs': [
-                  '<(gtest_dir)/../..',
-                ],
-                'defines': [
-                  'GUNIT_NO_GOOGLE3=1',
-                ],
-              },
-            }],
-          ],
-        },
-        {
-          'target_name': 'gtest_main',
-          'type': 'static_library',
-          'dependencies': [
-            'gtest',
-          ],
-          'sources': [
-            '<(gtest_dir)/src/gtest_main.cc',
-          ],
-        },
-        {
-          'target_name': 'gtest_test_executable',
-          'type': 'none',
-          'dependencies': [
-            'gtest',
-          ],
-          'direct_dependent_settings': {
-            'type': 'executable',
-            'include_dirs': [
-              '<(gtest_dir)',
-            ],
-          },
-          'export_dependent_settings': [
-            'gtest',
-          ],
-        },
-        {
-          'target_name': 'gtest_all_test',
-          'dependencies': [
-            'gtest_test_executable',
-            'gtest_main',
-          ],
-          'sources': [
-            '<(gtest_dir)/test/gtest-death-test_test.cc',
-            '<(gtest_dir)/test/gtest-filepath_test.cc',
-            '<(gtest_dir)/test/gtest-linked_ptr_test.cc',
-            '<(gtest_dir)/test/gtest-message_test.cc',
-            '<(gtest_dir)/test/gtest-options_test.cc',
-            '<(gtest_dir)/test/gtest-port_test.cc',
-            '<(gtest_dir)/test/gtest-printers_test.cc',
-            '<(gtest_dir)/test/gtest-test-part_test.cc',
-            '<(gtest_dir)/test/gtest-typed-test2_test.cc',
-            '<(gtest_dir)/test/gtest-typed-test_test.cc',
-            '<(gtest_dir)/test/gtest-typed-test_test.h',
-            '<(gtest_dir)/test/gtest_main_unittest.cc',
-            '<(gtest_dir)/test/gtest_pred_impl_unittest.cc',
-            '<(gtest_dir)/test/gtest_prod_test.cc',
-            '<(gtest_dir)/test/gtest_unittest.cc',
-            '<(gtest_dir)/test/production.cc',
-            '<(gtest_dir)/test/production.h',
-          ],
-        },
-        {
-          'target_name': 'gtest_environment_test',
-          'dependencies': [
-            'gtest_test_executable',
-          ],
-          'sources': [
-            '<(gtest_dir)/test/gtest_environment_test.cc',
-          ],
-        },
-        {
-          'target_name': 'gtest_listener_test',
-          'dependencies': [
-            'gtest_test_executable',
-          ],
-          'sources': [
-            '<(gtest_dir)/test/gtest-listener_test.cc',
-          ],
-        },
-        {
-          'target_name': 'gtest_no_test',
-          'dependencies': [
-            'gtest_test_executable',
-          ],
-          'sources': [
-            '<(gtest_dir)/test/gtest_no_test_unittest.cc',
-          ],
-        },
-        {
-          'target_name': 'gtest_param_test',
-          'dependencies': [
-            'gtest_test_executable',
-          ],
-          'sources': [
-            '<(gtest_dir)/test/gtest-param-test2_test.cc',
-            '<(gtest_dir)/test/gtest-param-test_test.cc',
-            '<(gtest_dir)/test/gtest-param-test_test.h',
-          ],
-        },
-        {
-          'target_name': 'gtest_premature_exit_test',
-          'dependencies': [
-            'gtest_test_executable',
-          ],
-          'sources': [
-            '<(gtest_dir)/test/gtest_premature_exit_test.cc',
-          ],
-        },
-        {
-          'target_name': 'gtest_repeat_test',
-          'dependencies': [
-            'gtest_test_executable',
-          ],
-          'sources': [
-            '<(gtest_dir)/test/gtest_repeat_test.cc',
-          ],
-        },
-        {
-          'target_name': 'gtest_sole_header_test',
-          'dependencies': [
-            'gtest_test_executable',
-            'gtest_main',
-          ],
-          'sources': [
-            '<(gtest_dir)/test/gtest_sole_header_test.cc',
-          ],
-        },
-        {
-          'target_name': 'gtest_stress_test',
-          'dependencies': [
-            'gtest_test_executable',
-          ],
-          'sources': [
-            '<(gtest_dir)/test/gtest_stress_test.cc',
-          ],
-        },
-        {
-          'target_name': 'gtest_unittest_api_test',
-          'dependencies': [
-            'gtest_test_executable',
-          ],
-          'sources': [
-            '<(gtest_dir)/test/gtest-unittest-api_test.cc',
-          ],
-        },
-        {
-          'target_name': 'gtest_all_tests',
-          'type': 'none',
-          'dependencies': [
-            'gtest_all_test',
-            'gtest_environment_test',
-            'gtest_listener_test',
-            'gtest_no_test',
-            'gtest_param_test',
-            'gtest_premature_exit_test',
-            'gtest_repeat_test',
-            'gtest_sole_header_test',
-            'gtest_stress_test',
-            'gtest_unittest_api_test',
-          ],
-        },
-      ],
-    }, {  # else: crashpad_dependencies=="chromium"
-      'targets': [
-        {
-          'target_name': 'gtest',
-          'type': 'none',
-          'dependencies': [
-            '<(DEPTH)/testing/gtest.gyp:gtest',
-          ],
-          'export_dependent_settings': [
-            '<(DEPTH)/testing/gtest.gyp:gtest',
-          ],
-        },
-        {
-          'target_name': 'gtest_main',
-          'type': 'none',
-          'dependencies': [
-            '<(DEPTH)/testing/gtest.gyp:gtest_main',
-          ],
-          'export_dependent_settings': [
-            '<(DEPTH)/testing/gtest.gyp:gtest_main',
-          ],
-        },
-      ],
     }],
   ],
+  'target_defaults': {
+    # gtest relies heavily on objects with static storage duration.
+    'xcode_settings': {
+      'WARNING_CFLAGS!': [
+        '-Wexit-time-destructors',
+      ],
+    },
+    'cflags!': [
+      '-Wexit-time-destructors',
+    ],
+  },
+
+  'targets': [
+    {
+      'target_name': 'gtest',
+      'type': 'static_library',
+      'include_dirs': [
+        '<(gtest_dir)',
+        '<(gtest_dir)/include',
+      ],
+      'sources': [
+        '<(gtest_dir)/include/gtest/gtest-death-test.h',
+        '<(gtest_dir)/include/gtest/gtest-message.h',
+        '<(gtest_dir)/include/gtest/gtest-param-test.h',
+        '<(gtest_dir)/include/gtest/gtest-printers.h',
+        '<(gtest_dir)/include/gtest/gtest-spi.h',
+        '<(gtest_dir)/include/gtest/gtest-test-part.h',
+        '<(gtest_dir)/include/gtest/gtest-typed-test.h',
+        '<(gtest_dir)/include/gtest/gtest.h',
+        '<(gtest_dir)/include/gtest/gtest_pred_impl.h',
+        '<(gtest_dir)/include/gtest/gtest_prod.h',
+        '<(gtest_dir)/include/gtest/internal/custom/gtest-port.h',
+        '<(gtest_dir)/include/gtest/internal/custom/gtest-printers.h',
+        '<(gtest_dir)/include/gtest/internal/custom/gtest.h',
+        '<(gtest_dir)/include/gtest/internal/gtest-death-test-internal.h',
+        '<(gtest_dir)/include/gtest/internal/gtest-filepath.h',
+        '<(gtest_dir)/include/gtest/internal/gtest-internal.h',
+        '<(gtest_dir)/include/gtest/internal/gtest-linked_ptr.h',
+        '<(gtest_dir)/include/gtest/internal/gtest-param-util-generated.h',
+        '<(gtest_dir)/include/gtest/internal/gtest-param-util.h',
+        '<(gtest_dir)/include/gtest/internal/gtest-port-arch.h',
+        '<(gtest_dir)/include/gtest/internal/gtest-port.h',
+        '<(gtest_dir)/include/gtest/internal/gtest-string.h',
+        '<(gtest_dir)/include/gtest/internal/gtest-tuple.h',
+        '<(gtest_dir)/include/gtest/internal/gtest-type-util.h',
+        '<(gtest_dir)/src/gtest-all.cc',
+        '<(gtest_dir)/src/gtest-death-test.cc',
+        '<(gtest_dir)/src/gtest-filepath.cc',
+        '<(gtest_dir)/src/gtest-internal-inl.h',
+        '<(gtest_dir)/src/gtest-port.cc',
+        '<(gtest_dir)/src/gtest-printers.cc',
+        '<(gtest_dir)/src/gtest-test-part.cc',
+        '<(gtest_dir)/src/gtest-typed-test.cc',
+        '<(gtest_dir)/src/gtest.cc',
+      ],
+      'sources!': [
+        '<(gtest_dir)/src/gtest-all.cc',
+      ],
+      'direct_dependent_settings': {
+        'include_dirs': [
+          '<(gtest_dir)/include',
+        ],
+      },
+      'conditions': [
+        ['crashpad_dependencies=="external"', {
+          'include_dirs': [
+            '<(gtest_dir)/../..',
+          ],
+          'defines': [
+            'GUNIT_NO_GOOGLE3=1',
+          ],
+          'direct_dependent_settings': {
+            'include_dirs': [
+              '<(gtest_dir)/../..',
+            ],
+            'defines': [
+              'GUNIT_NO_GOOGLE3=1',
+            ],
+          },
+        }],
+      ],
+    },
+    {
+      'target_name': 'gtest_main',
+      'type': 'static_library',
+      'dependencies': [
+        'gtest',
+      ],
+      'sources': [
+        '<(gtest_dir)/src/gtest_main.cc',
+      ],
+    },
+    {
+      'target_name': 'gtest_test_executable',
+      'type': 'none',
+      'dependencies': [
+        'gtest',
+      ],
+      'direct_dependent_settings': {
+        'type': 'executable',
+        'include_dirs': [
+          '<(gtest_dir)',
+        ],
+      },
+      'export_dependent_settings': [
+        'gtest',
+      ],
+    },
+    {
+      'target_name': 'gtest_all_test',
+      'dependencies': [
+        'gtest_test_executable',
+        'gtest_main',
+      ],
+      'sources': [
+        '<(gtest_dir)/test/gtest-death-test_test.cc',
+        '<(gtest_dir)/test/gtest-filepath_test.cc',
+        '<(gtest_dir)/test/gtest-linked_ptr_test.cc',
+        '<(gtest_dir)/test/gtest-message_test.cc',
+        '<(gtest_dir)/test/gtest-options_test.cc',
+        '<(gtest_dir)/test/gtest-port_test.cc',
+        '<(gtest_dir)/test/gtest-printers_test.cc',
+        '<(gtest_dir)/test/gtest-test-part_test.cc',
+        '<(gtest_dir)/test/gtest-typed-test2_test.cc',
+        '<(gtest_dir)/test/gtest-typed-test_test.cc',
+        '<(gtest_dir)/test/gtest-typed-test_test.h',
+        '<(gtest_dir)/test/gtest_main_unittest.cc',
+        '<(gtest_dir)/test/gtest_pred_impl_unittest.cc',
+        '<(gtest_dir)/test/gtest_prod_test.cc',
+        '<(gtest_dir)/test/gtest_unittest.cc',
+        '<(gtest_dir)/test/production.cc',
+        '<(gtest_dir)/test/production.h',
+      ],
+    },
+    {
+      'target_name': 'gtest_environment_test',
+      'dependencies': [
+        'gtest_test_executable',
+      ],
+      'sources': [
+        '<(gtest_dir)/test/gtest_environment_test.cc',
+      ],
+    },
+    {
+      'target_name': 'gtest_listener_test',
+      'dependencies': [
+        'gtest_test_executable',
+      ],
+      'sources': [
+        '<(gtest_dir)/test/gtest-listener_test.cc',
+      ],
+    },
+    {
+      'target_name': 'gtest_no_test',
+      'dependencies': [
+        'gtest_test_executable',
+      ],
+      'sources': [
+        '<(gtest_dir)/test/gtest_no_test_unittest.cc',
+      ],
+    },
+    {
+      'target_name': 'gtest_param_test',
+      'dependencies': [
+        'gtest_test_executable',
+      ],
+      'sources': [
+        '<(gtest_dir)/test/gtest-param-test2_test.cc',
+        '<(gtest_dir)/test/gtest-param-test_test.cc',
+        '<(gtest_dir)/test/gtest-param-test_test.h',
+      ],
+    },
+    {
+      'target_name': 'gtest_premature_exit_test',
+      'dependencies': [
+        'gtest_test_executable',
+      ],
+      'sources': [
+        '<(gtest_dir)/test/gtest_premature_exit_test.cc',
+      ],
+    },
+    {
+      'target_name': 'gtest_repeat_test',
+      'dependencies': [
+        'gtest_test_executable',
+      ],
+      'sources': [
+        '<(gtest_dir)/test/gtest_repeat_test.cc',
+      ],
+    },
+    {
+      'target_name': 'gtest_sole_header_test',
+      'dependencies': [
+        'gtest_test_executable',
+        'gtest_main',
+      ],
+      'sources': [
+        '<(gtest_dir)/test/gtest_sole_header_test.cc',
+      ],
+    },
+    {
+      'target_name': 'gtest_stress_test',
+      'dependencies': [
+        'gtest_test_executable',
+      ],
+      'sources': [
+        '<(gtest_dir)/test/gtest_stress_test.cc',
+      ],
+    },
+    {
+      'target_name': 'gtest_unittest_api_test',
+      'dependencies': [
+        'gtest_test_executable',
+      ],
+      'sources': [
+        '<(gtest_dir)/test/gtest-unittest-api_test.cc',
+      ],
+    },
+    {
+      'target_name': 'gtest_all_tests',
+      'type': 'none',
+      'dependencies': [
+        'gtest_all_test',
+        'gtest_environment_test',
+        'gtest_listener_test',
+        'gtest_no_test',
+        'gtest_param_test',
+        'gtest_premature_exit_test',
+        'gtest_repeat_test',
+        'gtest_sole_header_test',
+        'gtest_stress_test',
+        'gtest_unittest_api_test',
+      ],
+    },
+  ],
 }
diff --git a/third_party/mini_chromium/mini_chromium.gyp b/third_party/mini_chromium/mini_chromium.gyp
index f063dd0a..e14a1fa5 100644
--- a/third_party/mini_chromium/mini_chromium.gyp
+++ b/third_party/mini_chromium/mini_chromium.gyp
@@ -18,11 +18,10 @@
   ],
   'targets': [
     {
-      # To support Crashpad’s standalone build, its in-Chromium build, and its
-      # build depending on external libraries, Crashpad code depending on base
-      # should do so through this shim, which will either get base from
-      # mini_chromium, Chromium, or an external library depending on the build
-      # type.
+      # To support Crashpad’s standalone build and its build depending on
+      # external libraries, Crashpad code depending on base should do so through
+      # this shim, which will either get base from mini_chromium or an external
+      # library depending on the build type.
       'target_name': 'base',
       'type': 'none',
       'conditions': [
@@ -34,14 +33,6 @@
             'mini_chromium/base/base.gyp:base',
           ],
         }],
-        ['crashpad_dependencies=="chromium"', {
-          'dependencies': [
-            '<(DEPTH)/base/base.gyp:base',
-          ],
-          'export_dependent_settings': [
-            '<(DEPTH)/base/base.gyp:base',
-          ],
-        }],
         ['crashpad_dependencies=="external"', {
           'dependencies': [
             '../../../../mini_chromium/mini_chromium/base/base.gyp:base',
diff --git a/third_party/zlib/README.crashpad b/third_party/zlib/README.crashpad
new file mode 100644
index 00000000..83f47e31
--- /dev/null
+++ b/third_party/zlib/README.crashpad
@@ -0,0 +1,18 @@
+Name: zlib
+Short Name: zlib
+URL: http://zlib.net/
+Revision: See zlib/README.chromium
+License: zlib
+License File: zlib/LICENSE
+Security Critical: yes
+
+Description:
+“A massively spiffy yet delicately unobtrusive compression library.”
+
+zlib is a free, general-purpose, legally unencumbered lossless data-compression
+library. zlib implements the “deflate” compression algorithm described by RFC
+1951, which combines the LZ77 (Lempel-Ziv) algorithm with Huffman coding. zlib
+also implements the zlib (RFC 1950) and gzip (RFC 1952) wrapper formats.
+
+Local Modifications:
+See zlib/README.chromium.
diff --git a/third_party/zlib/zlib.gyp b/third_party/zlib/zlib.gyp
new file mode 100644
index 00000000..f92cdf26
--- /dev/null
+++ b/third_party/zlib/zlib.gyp
@@ -0,0 +1,137 @@
+# Copyright 2017 The Crashpad Authors. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+{
+  'variables': {
+    'conditions': [
+      # Use the system zlib by default where available, as it is on most
+      # platforms. Windows does not have a system zlib, so use “embedded” which
+      # directs the build to use the source code in the zlib subdirectory.
+      ['OS!="win"', {
+        'zlib_source%': 'system',
+      }, {
+        'zlib_source%': 'embedded',
+      }],
+    ],
+  },
+  'targets': [
+    {
+      'target_name': 'zlib',
+      'conditions': [
+        ['zlib_source=="system"', {
+          'type': 'none',
+          'direct_dependent_settings': {
+            'defines': [
+              'CRASHPAD_ZLIB_SOURCE_SYSTEM',
+            ],
+          },
+          'link_settings': {
+            'conditions': [
+              ['OS=="mac"', {
+                'libraries': [
+                  '$(SDKROOT)/usr/lib/libz.dylib',
+                ],
+              }, {
+                'libraries': [
+                  '-lz',
+                ],
+              }],
+            ],
+          },
+        }],
+        ['zlib_source=="embedded"', {
+          'type': 'static_library',
+          'include_dirs': [
+              'zlib',
+          ],
+          'defines': [
+            'CRASHPAD_ZLIB_SOURCE_EMBEDDED',
+            'HAVE_STDARG_H',
+          ],
+          'direct_dependent_settings': {
+            'include_dirs': [
+              'zlib',
+            ],
+            'defines': [
+              'CRASHPAD_ZLIB_SOURCE_EMBEDDED',
+            ],
+          },
+          'sources': [
+            'zlib/adler32.c',
+            'zlib/compress.c',
+            'zlib/crc32.c',
+            'zlib/crc32.h',
+            'zlib/crc_folding.c',
+            'zlib/deflate.c',
+            'zlib/deflate.h',
+            'zlib/fill_window_sse.c',
+            'zlib/gzclose.c',
+            'zlib/gzguts.h',
+            'zlib/gzlib.c',
+            'zlib/gzread.c',
+            'zlib/gzwrite.c',
+            'zlib/infback.c',
+            'zlib/inffast.c',
+            'zlib/inffast.h',
+            'zlib/inffixed.h',
+            'zlib/inflate.c',
+            'zlib/inflate.h',
+            'zlib/inftrees.c',
+            'zlib/inftrees.h',
+            'zlib/names.h',
+            'zlib/simd_stub.c',
+            'zlib/trees.c',
+            'zlib/trees.h',
+            'zlib/uncompr.c',
+            'zlib/x86.c',
+            'zlib/x86.h',
+            'zlib/zconf.h',
+            'zlib/zlib.h',
+            'zlib/zutil.c',
+            'zlib/zutil.h',
+            'zlib_crashpad.h',
+          ],
+          'conditions': [
+            ['target_arch=="x86" or target_arch=="amd64"', {
+              'sources!': [
+                'zlib/simd_stub.c',
+              ],
+            }, {
+              'sources!': [
+                'zlib/crc_folding.c',
+                'zlib/fill_window_sse.c',
+                'zlib/x86.c',
+                'zlib/x86.h',
+              ],
+            }],
+            ['OS!="win"', {
+              'defines': [
+                'HAVE_HIDDEN',
+                'HAVE_UNISTD_H',
+              ],
+            }, {
+              'msvs_disabled_warnings': [
+                4131,  # uses old-style declarator
+                4244,  # conversion from 't1' to 't2', possible loss of data
+                4245,  # conversion from 't1' to 't2', signed/unsigned mismatch
+                4267,  # conversion from 'size_t' to 't', possible loss of data
+                4324,  # structure was padded due to alignment specifier
+              ],
+            }],
+          ],
+        }],
+      ],
+    },
+  ],
+}
diff --git a/third_party/zlib/zlib_crashpad.h b/third_party/zlib/zlib_crashpad.h
new file mode 100644
index 00000000..2ab542e0
--- /dev/null
+++ b/third_party/zlib/zlib_crashpad.h
@@ -0,0 +1,32 @@
+// Copyright 2017 The Crashpad Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef CRASHPAD_THIRD_PARTY_ZLIB_ZLIB_CRASHPAD_H_
+#define CRASHPAD_THIRD_PARTY_ZLIB_ZLIB_CRASHPAD_H_
+
+// #include this file instead of the system version of <zlib.h> or equivalent
+// available at any other location in the source tree. It will #include the
+// proper <zlib.h> depending on how the build has been configured.
+
+#if defined(CRASHPAD_ZLIB_SOURCE_SYSTEM)
+#include <zlib.h>
+#elif defined(CRASHPAD_ZLIB_SOURCE_EMBEDDED)
+#include "third_party/zlib/zlib/zlib.h"
+#elif defined(CRASHPAD_ZLIB_SOURCE_CHROMIUM)
+#include "third_party/zlib/zlib.h"
+#else
+#error Unknown zlib source
+#endif
+
+#endif  // CRASHPAD_THIRD_PARTY_ZLIB_ZLIB_CRASHPAD_H_
diff --git a/util/mach/mig.py b/util/mach/mig.py
index eca2348a..a41c4f89 100755
--- a/util/mach/mig.py
+++ b/util/mach/mig.py
@@ -15,6 +15,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import argparse
 import os
 import re
 import subprocess
@@ -107,23 +108,32 @@ extern "C" {
   file.close()
 
 def main(args):
-  if len(args) == 5:
-    (defs_file, user_c, server_c, user_h, server_h) = args
-  elif len(args) == 6:
-    (defs_file, user_c, server_c, user_h, server_h, dev_dir) = args
-    os.environ['DEVELOPER_DIR'] = dev_dir
-  else:
-    assert False, "Wrong number of arguments"
-  subprocess.check_call(['mig',
-                         '-user', user_c,
-                         '-server', server_c,
-                         '-header', user_h,
-                         '-sheader', server_h,
-                         defs_file])
-  FixUserImplementation(user_c)
-  server_declarations = FixServerImplementation(server_c)
-  FixHeader(user_h)
-  FixHeader(server_h, server_declarations)
+  parser = argparse.ArgumentParser()
+  parser.add_argument('--developer-dir', help='Path to Xcode')
+  parser.add_argument('--sdk', help='Path to SDK')
+  parser.add_argument('defs')
+  parser.add_argument('user_c')
+  parser.add_argument('server_c')
+  parser.add_argument('user_h')
+  parser.add_argument('server_h')
+  parsed = parser.parse_args(args)
+
+  command = ['mig',
+             '-user', parsed.user_c,
+             '-server', parsed.server_c,
+             '-header', parsed.user_h,
+             '-sheader', parsed.server_h,
+            ]
+  if parsed.sdk is not None:
+    command.extend(['-isysroot', parsed.sdk])
+  if parsed.developer_dir is not None:
+    os.environ['DEVELOPER_DIR'] = parsed.developer_dir
+  command.append(parsed.defs)
+  subprocess.check_call(command)
+  FixUserImplementation(parsed.user_c)
+  server_declarations = FixServerImplementation(parsed.server_c)
+  FixHeader(parsed.user_h)
+  FixHeader(parsed.server_h, server_declarations)
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv[1:]))
diff --git a/util/misc/metrics.cc b/util/misc/metrics.cc
index 48be7ecd..e2bd9f0b 100644
--- a/util/misc/metrics.cc
+++ b/util/misc/metrics.cc
@@ -98,6 +98,14 @@ void Metrics::ExceptionEncountered() {
   ExceptionProcessing(ExceptionProcessingState::kStarted);
 }
 
+// static
+void Metrics::HandlerLifetimeMilestone(LifetimeMilestone milestone) {
+  UMA_HISTOGRAM_ENUMERATION("Crashpad.HandlerLifetimeMilestone",
+                            static_cast<int32_t>(milestone),
+                            static_cast<int32_t>(LifetimeMilestone::kMaxValue));
+}
+
+// static
 void Metrics::HandlerCrashed(uint32_t exception_code) {
   UMA_HISTOGRAM_SPARSE_SLOWLY(
       "Crashpad.HandlerCrash.ExceptionCode." METRICS_OS_NAME,
diff --git a/util/misc/metrics.h b/util/misc/metrics.h
index fd2e1200..b4bea910 100644
--- a/util/misc/metrics.h
+++ b/util/misc/metrics.h
@@ -30,8 +30,10 @@ namespace crashpad {
 //! Chromium's base, they allow integration with its metrics system.
 class Metrics {
  public:
-  //! \brief Values for CrashReportPending(). These are used as metrics
-  //!     enumeration values, so new values should always be added at the end.
+  //! \brief Values for CrashReportPending().
+  //!
+  //! \note These are used as metrics enumeration values, so new values should
+  //!     always be added at the end, before PendingReportReason::kMaxValue.
   enum class PendingReportReason : int32_t {
     //! \brief A report was newly created and is ready for upload.
     kNewlyCreated = 0,
@@ -53,8 +55,10 @@ class Metrics {
   //! \brief Reports on a crash upload attempt, and if it succeeded.
   static void CrashUploadAttempted(bool successful);
 
-  //! \brief Values for CrashUploadSkipped(). These are used as metrics
-  //!     enumeration values, so new values should always be added at the end.
+  //! \brief Values for CrashUploadSkipped().
+  //!
+  //! \note These are used as metrics enumeration values, so new values should
+  //!     always be added at the end, before CrashSkippedReason::kMaxValue.
   enum class CrashSkippedReason : int32_t {
     //! \brief Crash uploading is disabled.
     kUploadsDisabled = 0,
@@ -81,8 +85,10 @@ class Metrics {
   //!     database, without the report being uploadad.
   static void CrashUploadSkipped(CrashSkippedReason reason);
 
-  //! \brief The result of capturing an exception. These are used as metrics
-  //!     enumeration values, so new values should always be added at the end.
+  //! \brief The result of capturing an exception.
+  //!
+  //! \note These are used as metrics enumeration values, so new values should
+  //!     always be added at the end, before CaptureResult::kMaxValue.
   enum class CaptureResult : int32_t {
     //! \brief The exception capture succeeded normally.
     kSuccess = 0,
@@ -130,6 +136,37 @@ class Metrics {
   //! \brief The exception handler server started capturing an exception.
   static void ExceptionEncountered();
 
+  //! \brief An important event in a handler process’ lifetime.
+  //!
+  //! \note These are used as metrics enumeration values, so new values should
+  //!     always be added at the end, before LifetimeMilestone::kMaxValue.
+  enum class LifetimeMilestone : int32_t {
+    //! \brief The handler process started.
+    kStarted = 0,
+
+    //! \brief The handler process exited normally and cleanly.
+    kExitedNormally,
+
+    //! \brief The handler process exited early, but was successful in
+    //!     performing some non-default action on user request.
+    kExitedEarly,
+
+    //! \brief The handler process exited with a failure code.
+    kFailed,
+
+    //! \brief The handler process was forcibly terminated.
+    kTerminated,
+
+    //! \brief The handler process crashed.
+    kCrashed,
+
+    //! \brief The number of values in this enumeration; not a valid value.
+    kMaxValue
+  };
+
+  //! \brief Records a handler start/exit/crash event.
+  static void HandlerLifetimeMilestone(LifetimeMilestone milestone);
+
   //! \brief The handler process crashed with the given exception code.
   //!
   //! This is currently only reported on Windows.
diff --git a/util/misc/zlib.cc b/util/misc/zlib.cc
new file mode 100644
index 00000000..b26f9c90
--- /dev/null
+++ b/util/misc/zlib.cc
@@ -0,0 +1,37 @@
+// Copyright 2017 The Crashpad Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "util/misc/zlib.h"
+
+#include "base/logging.h"
+#include "base/strings/stringprintf.h"
+#include "third_party/zlib/zlib_crashpad.h"
+
+namespace crashpad {
+
+int ZlibWindowBitsWithGzipWrapper(int window_bits) {
+  // See the documentation for deflateInit2() and inflateInit2() in <zlib.h>. 0
+  // is only valid during decompression.
+
+  DCHECK(window_bits == 0 || (window_bits >= 8 && window_bits <= 15))
+      << window_bits;
+
+  return 16 + window_bits;
+}
+
+std::string ZlibErrorString(int zr) {
+  return base::StringPrintf("%s (%d)", zError(zr), zr);
+}
+
+}  // namespace crashpad
diff --git a/util/misc/zlib.h b/util/misc/zlib.h
new file mode 100644
index 00000000..99a9c91f
--- /dev/null
+++ b/util/misc/zlib.h
@@ -0,0 +1,42 @@
+// Copyright 2017 The Crashpad Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef CRASHPAD_UTIL_MISC_ZLIB_H_
+#define CRASHPAD_UTIL_MISC_ZLIB_H_
+
+#include <string>
+
+namespace crashpad {
+
+//! \brief Obtain a \a window_bits parameter to pass to `deflateInit2()` or
+//!     `inflateInit2()` that specifies a `gzip` wrapper instead of the default
+//!     zlib wrapper.
+//!
+//! \param[in] window_bits A \a window_bits value that only specifies the base-2
+//!     logarithm of the deflate sliding window size.
+//!
+//! \return \a window_bits adjusted to specify a `gzip` wrapper, to be passed to
+//!     `deflateInit2()` or `inflateInit2()`.
+int ZlibWindowBitsWithGzipWrapper(int window_bits);
+
+//! \brief Formats a string for an error received from the zlib library.
+//!
+//! \param[in] zr A zlib result code, such as `Z_STREAM_ERROR`.
+//!
+//! \return A formatted string.
+std::string ZlibErrorString(int zr);
+
+}  // namespace crashpad
+
+#endif  // CRASHPAD_UTIL_MISC_ZLIB_H_
diff --git a/util/net/http_body_gzip.cc b/util/net/http_body_gzip.cc
new file mode 100644
index 00000000..70f4db35
--- /dev/null
+++ b/util/net/http_body_gzip.cc
@@ -0,0 +1,126 @@
+// Copyright 2017 The Crashpad Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "util/net/http_body_gzip.h"
+
+#include <utility>
+
+#include "base/logging.h"
+#include "base/numerics/safe_conversions.h"
+#include "third_party/zlib/zlib_crashpad.h"
+#include "util/misc/zlib.h"
+
+namespace crashpad {
+
+GzipHTTPBodyStream::GzipHTTPBodyStream(std::unique_ptr<HTTPBodyStream> source)
+    : input_(),
+      source_(std::move(source)),
+      z_stream_(new z_stream()),
+      state_(State::kUninitialized) {}
+
+GzipHTTPBodyStream::~GzipHTTPBodyStream() {
+  DCHECK(state_ == State::kUninitialized ||
+         state_ == State::kFinished ||
+         state_ == State::kError);
+}
+
+FileOperationResult GzipHTTPBodyStream::GetBytesBuffer(uint8_t* buffer,
+                                                       size_t max_len) {
+  if (state_ == State::kError) {
+    return -1;
+  }
+
+  if (state_ == State::kFinished) {
+    return 0;
+  }
+
+  if (state_ == State::kUninitialized) {
+    z_stream_->zalloc = Z_NULL;
+    z_stream_->zfree = Z_NULL;
+    z_stream_->opaque = Z_NULL;
+
+    // The default values for zlib’s internal MAX_WBITS and DEF_MEM_LEVEL. These
+    // are the values that deflateInit() would use, but they’re not exported
+    // from zlib. deflateInit2() is used instead of deflateInit() to get the
+    // gzip wrapper.
+    const int kZlibMaxWindowBits = 15;
+    const int kZlibDefaultMemoryLevel = 8;
+
+    int zr = deflateInit2(z_stream_.get(),
+                          Z_DEFAULT_COMPRESSION,
+                          Z_DEFLATED,
+                          ZlibWindowBitsWithGzipWrapper(kZlibMaxWindowBits),
+                          kZlibDefaultMemoryLevel,
+                          Z_DEFAULT_STRATEGY);
+    if (zr != Z_OK) {
+      LOG(ERROR) << "deflateInit2: " << ZlibErrorString(zr);
+      state_ = State::kError;
+      return -1;
+    }
+
+    state_ = State::kOperating;
+  }
+
+  z_stream_->next_out = buffer;
+  z_stream_->avail_out = base::saturated_cast<uInt>(max_len);
+
+  while (state_ != State::kFinished && z_stream_->avail_out > 0) {
+    if (state_ != State::kInputEOF && z_stream_->avail_in == 0) {
+      FileOperationResult input_bytes =
+          source_->GetBytesBuffer(input_, sizeof(input_));
+      if (input_bytes == -1) {
+        Done(State::kError);
+        return -1;
+      }
+
+      if (input_bytes == 0) {
+        state_ = State::kInputEOF;
+      }
+
+      z_stream_->next_in = input_;
+      z_stream_->avail_in = base::checked_cast<uInt>(input_bytes);
+    }
+
+    int zr = deflate(z_stream_.get(),
+                     state_ == State::kInputEOF ? Z_FINISH : Z_NO_FLUSH);
+    if (state_ == State::kInputEOF && zr == Z_STREAM_END) {
+      Done(State::kFinished);
+      if (state_ == State::kError) {
+        return -1;
+      }
+    } else if (zr != Z_OK) {
+      LOG(ERROR) << "deflate: " << ZlibErrorString(zr);
+      Done(State::kError);
+      return -1;
+    }
+  }
+
+  DCHECK_LE(z_stream_->avail_out, max_len);
+  return max_len - z_stream_->avail_out;
+}
+
+void GzipHTTPBodyStream::Done(State state) {
+  DCHECK(state_ == State::kOperating || state_ == State::kInputEOF) << state_;
+  DCHECK(state == State::kFinished || state == State::kError) << state;
+
+  int zr = deflateEnd(z_stream_.get());
+  if (zr != Z_OK) {
+    LOG(ERROR) << "deflateEnd: " << ZlibErrorString(zr);
+    state_ = State::kError;
+  } else {
+    state_ = state;
+  }
+}
+
+}  // namespace crashpad
diff --git a/util/net/http_body_gzip.h b/util/net/http_body_gzip.h
new file mode 100644
index 00000000..da3a5f24
--- /dev/null
+++ b/util/net/http_body_gzip.h
@@ -0,0 +1,67 @@
+// Copyright 2017 The Crashpad Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef CRASHPAD_UTIL_NET_HTTP_BODY_GZIP_H_
+#define CRASHPAD_UTIL_NET_HTTP_BODY_GZIP_H_
+
+#include <stdint.h>
+#include <sys/types.h>
+
+#include <memory>
+
+#include "base/macros.h"
+#include "util/file/file_io.h"
+#include "util/net/http_body.h"
+
+extern "C" {
+typedef struct z_stream_s z_stream;
+}  // extern "C"
+
+namespace crashpad {
+
+//! \brief An implementation of HTTPBodyStream that `gzip`-compresses another
+//!     HTTPBodyStream.
+class GzipHTTPBodyStream : public HTTPBodyStream {
+ public:
+  explicit GzipHTTPBodyStream(std::unique_ptr<HTTPBodyStream> source);
+
+  ~GzipHTTPBodyStream() override;
+
+  // HTTPBodyStream:
+  FileOperationResult GetBytesBuffer(uint8_t* buffer, size_t max_len) override;
+
+ private:
+  enum State : int {
+    kUninitialized,
+    kOperating,
+    kInputEOF,
+    kFinished,
+    kError,
+  };
+
+  // Calls deflateEnd() and transitions state_ to state. If deflateEnd() fails,
+  // logs a message and transitions state_ to State::kError.
+  void Done(State state);
+
+  uint8_t input_[4096];
+  std::unique_ptr<HTTPBodyStream> source_;
+  std::unique_ptr<z_stream> z_stream_;
+  State state_;
+
+  DISALLOW_COPY_AND_ASSIGN(GzipHTTPBodyStream);
+};
+
+}  // namespace crashpad
+
+#endif  // CRASHPAD_UTIL_NET_HTTP_BODY_GZIP_H_
diff --git a/util/net/http_body_gzip_test.cc b/util/net/http_body_gzip_test.cc
new file mode 100644
index 00000000..a7b97b93
--- /dev/null
+++ b/util/net/http_body_gzip_test.cc
@@ -0,0 +1,178 @@
+// Copyright 2017 The Crashpad Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "util/net/http_body_gzip.h"
+
+#include <string.h>
+
+#include <algorithm>
+#include <memory>
+#include <string>
+#include <utility>
+
+#include "base/macros.h"
+#include "base/rand_util.h"
+#include "base/numerics/safe_conversions.h"
+#include "gtest/gtest.h"
+#include "third_party/zlib/zlib_crashpad.h"
+#include "util/misc/zlib.h"
+#include "util/net/http_body.h"
+
+namespace crashpad {
+namespace test {
+namespace {
+
+class ScopedZlibInflateStream {
+ public:
+  explicit ScopedZlibInflateStream(z_stream* zlib) : zlib_(zlib) {}
+  ~ScopedZlibInflateStream() {
+    int zr = inflateEnd(zlib_);
+    EXPECT_EQ(Z_OK, zr) << "inflateEnd: " << ZlibErrorString(zr);
+  }
+
+ private:
+  z_stream* zlib_;  // weak
+  DISALLOW_COPY_AND_ASSIGN(ScopedZlibInflateStream);
+};
+
+void GzipInflate(const std::string& compressed,
+                 std::string* decompressed,
+                 size_t buf_size) {
+  decompressed->clear();
+
+  // There’s got to be at least a small buffer.
+  buf_size = std::max(buf_size, static_cast<size_t>(1));
+
+  std::unique_ptr<uint8_t[]> buf(new uint8_t[buf_size]);
+  z_stream zlib = {};
+  zlib.zalloc = Z_NULL;
+  zlib.zfree = Z_NULL;
+  zlib.opaque = Z_NULL;
+  zlib.next_in = reinterpret_cast<Bytef*>(const_cast<char*>(&compressed[0]));
+  zlib.avail_in = base::checked_cast<uInt>(compressed.size());
+  zlib.next_out = buf.get();
+  zlib.avail_out = base::checked_cast<uInt>(buf_size);
+
+  int zr = inflateInit2(&zlib, ZlibWindowBitsWithGzipWrapper(0));
+  ASSERT_EQ(Z_OK, zr) << "inflateInit2: " << ZlibErrorString(zr);
+  ScopedZlibInflateStream zlib_inflate(&zlib);
+
+  zr = inflate(&zlib, Z_FINISH);
+  ASSERT_EQ(Z_STREAM_END, zr) << "inflate: " << ZlibErrorString(zr);
+
+  ASSERT_LE(zlib.avail_out, buf_size);
+  decompressed->assign(reinterpret_cast<char*>(buf.get()),
+                       buf_size - zlib.avail_out);
+}
+
+void TestGzipDeflateInflate(const std::string& string) {
+  std::unique_ptr<HTTPBodyStream> string_stream(
+      new StringHTTPBodyStream(string));
+  GzipHTTPBodyStream gzip_stream(std::move(string_stream));
+
+  // The minimum size of a gzip wrapper per RFC 1952: a 10-byte header and an
+  // 8-byte trailer.
+  const size_t kGzipHeaderSize = 18;
+
+  // Per http://www.zlib.net/zlib_tech.html, in the worst case, zlib will store
+  // uncompressed data as-is, at an overhead of 5 bytes per 16384-byte block.
+  // Zero-length input will “compress” to a 2-byte zlib stream. Add the overhead
+  // of the gzip wrapper, assuming no optional fields are present.
+  size_t buf_size =
+      string.size() + kGzipHeaderSize +
+      (string.empty() ? 2 : (((string.size() + 16383) / 16384) * 5));
+  std::unique_ptr<uint8_t[]> buf(new uint8_t[buf_size]);
+  FileOperationResult compressed_bytes =
+      gzip_stream.GetBytesBuffer(buf.get(), buf_size);
+  ASSERT_NE(compressed_bytes, -1);
+  ASSERT_LE(static_cast<size_t>(compressed_bytes), buf_size);
+
+  // Make sure that the stream is really at EOF.
+  uint8_t eof_buf[16];
+  ASSERT_EQ(0, gzip_stream.GetBytesBuffer(eof_buf, sizeof(eof_buf)));
+
+  std::string compressed(reinterpret_cast<char*>(buf.get()), compressed_bytes);
+
+  ASSERT_GE(compressed.size(), kGzipHeaderSize);
+  EXPECT_EQ('\37', compressed[0]);
+  EXPECT_EQ('\213', compressed[1]);
+  EXPECT_EQ(Z_DEFLATED, compressed[2]);
+
+  std::string decompressed;
+  ASSERT_NO_FATAL_FAILURE(
+      GzipInflate(compressed, &decompressed, string.size()));
+
+  EXPECT_EQ(string, decompressed);
+
+  // In block mode, compression should be identical.
+  string_stream.reset(new StringHTTPBodyStream(string));
+  GzipHTTPBodyStream block_gzip_stream(std::move(string_stream));
+  uint8_t block_buf[4096];
+  std::string block_compressed;
+  FileOperationResult block_compressed_bytes;
+  while ((block_compressed_bytes = block_gzip_stream.GetBytesBuffer(
+              block_buf, sizeof(block_buf))) > 0) {
+    block_compressed.append(reinterpret_cast<char*>(block_buf),
+                            block_compressed_bytes);
+  }
+  ASSERT_EQ(0, block_compressed_bytes);
+  EXPECT_EQ(compressed, block_compressed);
+}
+
+std::string MakeString(size_t size) {
+  std::string string;
+  for (size_t i = 0; i < size; ++i) {
+    string.append(1, (i % 256) ^ ((i >> 8) % 256));
+  }
+  return string;
+}
+
+constexpr size_t kFourKBytes = 4096;
+constexpr size_t kManyBytes = 375017;
+
+TEST(GzipHTTPBodyStream, Empty) {
+  TestGzipDeflateInflate(std::string());
+}
+
+TEST(GzipHTTPBodyStream, OneByte) {
+  TestGzipDeflateInflate(std::string("Z"));
+}
+
+TEST(GzipHTTPBodyStream, FourKBytes_NUL) {
+  TestGzipDeflateInflate(std::string(kFourKBytes, '\0'));
+}
+
+TEST(GzipHTTPBodyStream, ManyBytes_NUL) {
+  TestGzipDeflateInflate(std::string(kManyBytes, '\0'));
+}
+
+TEST(GzipHTTPBodyStream, FourKBytes_Deterministic) {
+  TestGzipDeflateInflate(MakeString(kFourKBytes));
+}
+
+TEST(GzipHTTPBodyStream, ManyBytes_Deterministic) {
+  TestGzipDeflateInflate(MakeString(kManyBytes));
+}
+
+TEST(GzipHTTPBodyStream, FourKBytes_Random) {
+  TestGzipDeflateInflate(base::RandBytesAsString(kFourKBytes));
+}
+
+TEST(GzipHTTPBodyStream, ManyBytes_Random) {
+  TestGzipDeflateInflate(base::RandBytesAsString(kManyBytes));
+}
+
+}  // namespace
+}  // namespace test
+}  // namespace crashpad
diff --git a/util/net/http_headers.cc b/util/net/http_headers.cc
index 09d61b3e..37d84c67 100644
--- a/util/net/http_headers.cc
+++ b/util/net/http_headers.cc
@@ -17,7 +17,7 @@
 namespace crashpad {
 
 const char kContentType[] = "Content-Type";
-
 const char kContentLength[] = "Content-Length";
+const char kContentEncoding[] = "Content-Encoding";
 
 }  // namespace crashpad
diff --git a/util/net/http_headers.h b/util/net/http_headers.h
index 3633cb2d..851ff31c 100644
--- a/util/net/http_headers.h
+++ b/util/net/http_headers.h
@@ -29,6 +29,9 @@ extern const char kContentType[];
 //! \brief The header name `"Content-Length"`.
 extern const char kContentLength[];
 
+//! \brief The header name `"Content-Encoding"`.
+extern const char kContentEncoding[];
+
 }  // namespace crashpad
 
 #endif  // CRASHPAD_UTIL_NET_HTTP_HEADERS_H_
diff --git a/util/net/http_multipart_builder.cc b/util/net/http_multipart_builder.cc
index 46f6f090..640d540a 100644
--- a/util/net/http_multipart_builder.cc
+++ b/util/net/http_multipart_builder.cc
@@ -23,6 +23,7 @@
 #include "base/rand_util.h"
 #include "base/strings/stringprintf.h"
 #include "util/net/http_body.h"
+#include "util/net/http_body_gzip.h"
 
 namespace crashpad {
 
@@ -116,12 +117,18 @@ void AssertSafeMIMEType(const std::string& string) {
 }  // namespace
 
 HTTPMultipartBuilder::HTTPMultipartBuilder()
-    : boundary_(GenerateBoundaryString()), form_data_(), file_attachments_() {
-}
+    : boundary_(GenerateBoundaryString()),
+      form_data_(),
+      file_attachments_(),
+      gzip_enabled_(false) {}
 
 HTTPMultipartBuilder::~HTTPMultipartBuilder() {
 }
 
+void HTTPMultipartBuilder::SetGzipEnabled(bool gzip_enabled) {
+  gzip_enabled_ = gzip_enabled;
+}
+
 void HTTPMultipartBuilder::SetFormData(const std::string& key,
                                        const std::string& value) {
   EraseKey(key);
@@ -179,13 +186,24 @@ std::unique_ptr<HTTPBodyStream> HTTPMultipartBuilder::GetBodyStream() {
   streams.push_back(
       new StringHTTPBodyStream("--"  + boundary_ + "--" + kCRLF));
 
-  return std::unique_ptr<HTTPBodyStream>(new CompositeHTTPBodyStream(streams));
+  auto composite =
+      std::unique_ptr<HTTPBodyStream>(new CompositeHTTPBodyStream(streams));
+  if (gzip_enabled_) {
+    return std::unique_ptr<HTTPBodyStream>(
+        new GzipHTTPBodyStream(std::move(composite)));
+  }
+  return composite;
 }
 
-HTTPHeaders::value_type HTTPMultipartBuilder::GetContentType() const {
+void HTTPMultipartBuilder::PopulateContentHeaders(
+    HTTPHeaders* http_headers) const {
   std::string content_type =
       base::StringPrintf("multipart/form-data; boundary=%s", boundary_.c_str());
-  return std::make_pair(kContentType, content_type);
+  (*http_headers)[kContentType] = content_type;
+
+  if (gzip_enabled_) {
+    (*http_headers)[kContentEncoding] = "gzip";
+  }
 }
 
 void HTTPMultipartBuilder::EraseKey(const std::string& key) {
diff --git a/util/net/http_multipart_builder.h b/util/net/http_multipart_builder.h
index 65602c71..e0c98fa4 100644
--- a/util/net/http_multipart_builder.h
+++ b/util/net/http_multipart_builder.h
@@ -34,6 +34,15 @@ class HTTPMultipartBuilder {
   HTTPMultipartBuilder();
   ~HTTPMultipartBuilder();
 
+  //! \brief Enables or disables `gzip` compression.
+  //!
+  //! \param[in] gzip_enabled Whether to enable or disable `gzip` compression.
+  //!
+  //! When `gzip` compression is enabled, the body stream returned by
+  //! GetBodyStream() will be `gzip`-compressed, and the content headers set by
+  //! PopulateContentHeaders() will contain `Content-Encoding: gzip`.
+  void SetGzipEnabled(bool gzip_enabled);
+
   //! \brief Sets a `Content-Disposition: form-data` key-value pair.
   //!
   //! \param[in] key The key of the form data, specified as the `name` in the
@@ -64,8 +73,11 @@ class HTTPMultipartBuilder {
   //! \return A caller-owned HTTPBodyStream object.
   std::unique_ptr<HTTPBodyStream> GetBodyStream();
 
-  //! \brief Gets the header pair for `"Content-Type"`.
-  HTTPHeaders::value_type GetContentType() const;
+  //! \brief Adds the appropriate content headers to \a http_headers.
+  //!
+  //! Any headers that this method adds will replace existing headers by the
+  //! same name in \a http_headers.
+  void PopulateContentHeaders(HTTPHeaders* http_headers) const;
 
  private:
   struct FileAttachment {
@@ -81,6 +93,7 @@ class HTTPMultipartBuilder {
   std::string boundary_;
   std::map<std::string, std::string> form_data_;
   std::map<std::string, FileAttachment> file_attachments_;
+  bool gzip_enabled_;
 
   DISALLOW_COPY_AND_ASSIGN(HTTPMultipartBuilder);
 };
diff --git a/util/net/http_multipart_builder_test.cc b/util/net/http_multipart_builder_test.cc
index d019d058..fa20abe4 100644
--- a/util/net/http_multipart_builder_test.cc
+++ b/util/net/http_multipart_builder_test.cc
@@ -71,6 +71,7 @@ TEST(HTTPMultipartBuilder, ThreeStringFields) {
   ASSERT_TRUE(body.get());
   std::string contents = ReadStreamToString(body.get());
   auto lines = SplitCRLF(contents);
+  ASSERT_EQ(13u, lines.size());
   auto lines_it = lines.begin();
 
   // The first line is the boundary. All subsequent boundaries must match this.
@@ -164,6 +165,7 @@ TEST(HTTPMultipartBuilder, OverwriteFormDataWithEscapedKey) {
   ASSERT_TRUE(body.get());
   std::string contents = ReadStreamToString(body.get());
   auto lines = SplitCRLF(contents);
+  ASSERT_EQ(5u, lines.size());
   auto lines_it = lines.begin();
 
   const std::string& boundary = *lines_it++;
@@ -253,6 +255,7 @@ TEST(HTTPMultipartBuilder, SharedFormDataAndAttachmentKeyNamespace) {
   ASSERT_TRUE(body.get());
   std::string contents = ReadStreamToString(body.get());
   auto lines = SplitCRLF(contents);
+  ASSERT_EQ(9u, lines.size());
   auto lines_it = lines.begin();
 
   const std::string& boundary = *lines_it++;
diff --git a/util/net/http_transport_test.cc b/util/net/http_transport_test.cc
index e8495308..8dfa68a4 100644
--- a/util/net/http_transport_test.cc
+++ b/util/net/http_transport_test.cc
@@ -221,7 +221,21 @@ TEST(HTTPTransport, ValidFormData) {
   builder.SetFormData("key2", "--abcdefg123");
 
   HTTPHeaders headers;
-  EXPECT_TRUE(headers.insert(builder.GetContentType()).second);
+  builder.PopulateContentHeaders(&headers);
+
+  HTTPTransportTestFixture test(
+      headers, builder.GetBodyStream(), 200, &ValidFormData);
+  test.Run();
+}
+
+TEST(HTTPTransport, ValidFormData_Gzip) {
+  HTTPMultipartBuilder builder;
+  builder.SetGzipEnabled(true);
+  builder.SetFormData("key1", "test");
+  builder.SetFormData("key2", "--abcdefg123");
+
+  HTTPHeaders headers;
+  builder.PopulateContentHeaders(&headers);
 
   HTTPTransportTestFixture test(headers, builder.GetBodyStream(), 200,
       &ValidFormData);
diff --git a/util/net/http_transport_test_server.py b/util/net/http_transport_test_server.py
index 3d3c55a4..7ea15719 100755
--- a/util/net/http_transport_test_server.py
+++ b/util/net/http_transport_test_server.py
@@ -33,6 +33,7 @@ This could easily have been written in C++ instead.
 import BaseHTTPServer
 import struct
 import sys
+import zlib
 
 class BufferedReadFile(object):
   """A File-like object that stores all read contents into a buffer."""
@@ -81,11 +82,20 @@ class RequestHandler(BaseHTTPServer.BaseHTTPRequestHandler):
     self.rfile.buffer = ''
 
     if self.headers.get('Transfer-Encoding', '').lower() == 'chunked':
+      if 'Content-Length' in self.headers:
+        raise AssertionError
       body = self.handle_chunked_encoding()
     else:
       length = int(self.headers.get('Content-Length', -1))
       body = self.rfile.read(length)
 
+    if self.headers.get('Content-Encoding', '').lower() == 'gzip':
+      # 15 is the value of |wbits|, which should be at the maximum possible
+      # value to ensure that any gzip stream can be decoded. The offset of 16
+      # specifies that the stream to decompress will be formatted with a gzip
+      # wrapper.
+      body = zlib.decompress(body, 16 + 15)
+
     RequestHandler.raw_request += body
 
     self.send_response(self.response_code)
diff --git a/util/thread/thread_posix.cc b/util/thread/thread_posix.cc
index 7142c786..58a98747 100644
--- a/util/thread/thread_posix.cc
+++ b/util/thread/thread_posix.cc
@@ -14,20 +14,22 @@
 
 #include "util/thread/thread.h"
 
+#include <errno.h>
+
 #include "base/logging.h"
 
 namespace crashpad {
 
 void Thread::Start() {
   DCHECK(!platform_thread_);
-  int rv = pthread_create(&platform_thread_, nullptr, ThreadEntryThunk, this);
-  PCHECK(0 == rv);
+  errno = pthread_create(&platform_thread_, nullptr, ThreadEntryThunk, this);
+  PCHECK(errno == 0) << "pthread_create";
 }
 
 void Thread::Join() {
   DCHECK(platform_thread_);
-  int rv = pthread_join(platform_thread_, nullptr);
-  PCHECK(0 == rv);
+  errno = pthread_join(platform_thread_, nullptr);
+  PCHECK(errno == 0) << "pthread_join";
   platform_thread_ = 0;
 }
 
diff --git a/util/thread/thread_win.cc b/util/thread/thread_win.cc
index c4ac1eb7..466dfa9b 100644
--- a/util/thread/thread_win.cc
+++ b/util/thread/thread_win.cc
@@ -22,13 +22,13 @@ void Thread::Start() {
   DCHECK(!platform_thread_);
   platform_thread_ =
       CreateThread(nullptr, 0, ThreadEntryThunk, this, 0, nullptr);
-  PCHECK(platform_thread_);
+  PCHECK(platform_thread_) << "CreateThread";
 }
 
 void Thread::Join() {
   DCHECK(platform_thread_);
   DWORD result = WaitForSingleObject(platform_thread_, INFINITE);
-  PCHECK(WAIT_OBJECT_0 == result);
+  PCHECK(result == WAIT_OBJECT_0) << "WaitForSingleObject";
   platform_thread_ = 0;
 }
 
diff --git a/util/util.gyp b/util/util.gyp
index abf0bfdc..b27337c6 100644
--- a/util/util.gyp
+++ b/util/util.gyp
@@ -23,6 +23,7 @@
       'dependencies': [
         '../compat/compat.gyp:crashpad_compat',
         '../third_party/mini_chromium/mini_chromium.gyp:base',
+        '../third_party/zlib/zlib.gyp:zlib',
       ],
       'include_dirs': [
         '..',
@@ -106,8 +107,12 @@
         'misc/tri_state.h',
         'misc/uuid.cc',
         'misc/uuid.h',
+        'misc/zlib.cc',
+        'misc/zlib.h',
         'net/http_body.cc',
         'net/http_body.h',
+        'net/http_body_gzip.cc',
+        'net/http_body_gzip.h',
         'net/http_headers.cc',
         'net/http_headers.h',
         'net/http_multipart_builder.cc',
@@ -193,6 +198,8 @@
         'win/scoped_local_alloc.h',
         'win/scoped_process_suspend.cc',
         'win/scoped_process_suspend.h',
+        'win/session_end_watcher.cc',
+        'win/session_end_watcher.h',
         'win/termination_codes.h',
         'win/time.cc',
         'win/time.h',
@@ -263,6 +270,7 @@
         ['OS=="win"', {
           'link_settings': {
             'libraries': [
+              '-luser32.lib',
               '-lwinhttp.lib',
             ],
           },
diff --git a/util/util_test.gyp b/util/util_test.gyp
index e6bf5635..e16a292f 100644
--- a/util/util_test.gyp
+++ b/util/util_test.gyp
@@ -29,6 +29,7 @@
         '../third_party/gtest/gmock.gyp:gmock_main',
         '../third_party/gtest/gtest.gyp:gtest',
         '../third_party/mini_chromium/mini_chromium.gyp:base',
+        '../third_party/zlib/zlib.gyp:zlib',
       ],
       'include_dirs': [
         '..',
@@ -62,6 +63,7 @@
         'misc/scoped_forbid_return_test.cc',
         'misc/random_string_test.cc',
         'misc/uuid_test.cc',
+        'net/http_body_gzip_test.cc',
         'net/http_body_test.cc',
         'net/http_body_test_util.cc',
         'net/http_body_test_util.h',
@@ -93,6 +95,7 @@
         'win/process_info_test.cc',
         'win/registration_protocol_win_test.cc',
         'win/scoped_process_suspend_test.cc',
+        'win/session_end_watcher_test.cc',
         'win/time_test.cc',
       ],
       'conditions': [
@@ -112,6 +115,7 @@
               '-ladvapi32.lib',
               '-limagehlp.lib',
               '-lrpcrt4.lib',
+              '-luser32.lib',
             ],
           },
         }],
diff --git a/util/win/scoped_handle.cc b/util/win/scoped_handle.cc
index 5eb440e0..57d28217 100644
--- a/util/win/scoped_handle.cc
+++ b/util/win/scoped_handle.cc
@@ -25,7 +25,7 @@ void ScopedFileHANDLECloseTraits::Free(HANDLE handle) {
 }
 
 void ScopedKernelHANDLECloseTraits::Free(HANDLE handle) {
-  PCHECK(CloseHandle(handle));
+  PCHECK(CloseHandle(handle)) << "CloseHandle";
 }
 
 }  // namespace internal
diff --git a/util/win/session_end_watcher.cc b/util/win/session_end_watcher.cc
new file mode 100644
index 00000000..e795f22a
--- /dev/null
+++ b/util/win/session_end_watcher.cc
@@ -0,0 +1,243 @@
+// Copyright 2017 The Crashpad Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "util/win/session_end_watcher.h"
+
+#include "base/logging.h"
+#include "base/scoped_generic.h"
+
+extern "C" {
+extern IMAGE_DOS_HEADER __ImageBase;
+}  // extern "C"
+
+namespace crashpad {
+
+namespace {
+
+class ScopedSetEvent {
+ public:
+  explicit ScopedSetEvent(HANDLE event) : event_(event) {}
+  ~ScopedSetEvent() {
+    if (!SetEvent(event_)) {
+      PLOG(ERROR) << "SetEvent";
+    }
+  }
+
+ private:
+  HANDLE event_;
+
+  DISALLOW_COPY_AND_ASSIGN(ScopedSetEvent);
+};
+
+// ScopedWindowClass and ScopedWindow operate on ATOM* and HWND*, respectively,
+// instead of ATOM and HWND, so that the actual storage can exist as a local
+// variable or a member variable, and the scoper can be responsible for
+// releasing things only if the actual storage hasn’t been released and zeroed
+// already by something else.
+struct ScopedWindowClassTraits {
+  static ATOM* InvalidValue() { return nullptr; }
+  static void Free(ATOM* window_class) {
+    if (*window_class) {
+      if (!UnregisterClass(MAKEINTATOM(*window_class), 0)) {
+        PLOG(ERROR) << "UnregisterClass";
+      } else {
+        *window_class = 0;
+      }
+    }
+  }
+};
+using ScopedWindowClass = base::ScopedGeneric<ATOM*, ScopedWindowClassTraits>;
+
+struct ScopedWindowTraits {
+  static HWND* InvalidValue() { return nullptr; }
+  static void Free(HWND* window) {
+    if (*window) {
+      if (!DestroyWindow(*window)) {
+        PLOG(ERROR) << "DestroyWindow";
+      } else {
+        *window = nullptr;
+      }
+    }
+  }
+};
+using ScopedWindow = base::ScopedGeneric<HWND*, ScopedWindowTraits>;
+
+// GetWindowLongPtr()’s return value doesn’t unambiguously indicate whether it
+// was successful, because 0 could either represent successful retrieval of the
+// value 0, or failure. This wrapper is more convenient to use.
+bool GetWindowLongPtrAndSuccess(HWND window, int index, LONG_PTR* value) {
+  SetLastError(ERROR_SUCCESS);
+  *value = GetWindowLongPtr(window, index);
+  return *value || GetLastError() == ERROR_SUCCESS;
+}
+
+// SetWindowLongPtr() has the same problem as GetWindowLongPtr(). Use this
+// wrapper instead.
+bool SetWindowLongPtrAndGetSuccess(HWND window, int index, LONG_PTR value) {
+  SetLastError(ERROR_SUCCESS);
+  LONG_PTR previous = SetWindowLongPtr(window, index, value);
+  return previous || GetLastError() == ERROR_SUCCESS;
+}
+
+}  // namespace
+
+SessionEndWatcher::SessionEndWatcher()
+    : Thread(),
+      window_(nullptr),
+      started_(nullptr),
+      stopped_(nullptr) {
+  // Set bManualReset for these events so that WaitForStart() and WaitForStop()
+  // can be called multiple times.
+
+  started_.reset(CreateEvent(nullptr, true, false, nullptr));
+  PLOG_IF(ERROR, !started_.get()) << "CreateEvent";
+
+  stopped_.reset(CreateEvent(nullptr, true, false, nullptr));
+  PLOG_IF(ERROR, !stopped_.get()) << "CreateEvent";
+
+  Start();
+}
+
+SessionEndWatcher::~SessionEndWatcher() {
+  // Tear everything down by posting a WM_CLOSE to the window. This obviously
+  // can’t work until the window has been created, and that happens on a
+  // different thread, so wait for the start event to be signaled first.
+  WaitForStart();
+  if (window_) {
+    if (!PostMessage(window_, WM_CLOSE, 0, 0)) {
+      PLOG(ERROR) << "PostMessage";
+    }
+  }
+
+  Join();
+  DCHECK(!window_);
+}
+
+void SessionEndWatcher::WaitForStart() {
+  if (WaitForSingleObject(started_.get(), INFINITE) != WAIT_OBJECT_0) {
+    PLOG(ERROR) << "WaitForSingleObject";
+  }
+}
+
+void SessionEndWatcher::WaitForStop() {
+  if (WaitForSingleObject(stopped_.get(), INFINITE) != WAIT_OBJECT_0) {
+    PLOG(ERROR) << "WaitForSingleObject";
+  }
+}
+
+void SessionEndWatcher::ThreadMain() {
+  ATOM atom = 0;
+  ScopedWindowClass window_class(&atom);
+  ScopedWindow window(&window_);
+
+  ScopedSetEvent call_set_stop(stopped_.get());
+
+  {
+    ScopedSetEvent call_set_start(started_.get());
+
+    WNDCLASS wndclass = {};
+    wndclass.lpfnWndProc = WindowProc;
+    wndclass.hInstance = reinterpret_cast<HMODULE>(&__ImageBase);
+    wndclass.lpszClassName = L"crashpad_SessionEndWatcher";
+    atom = RegisterClass(&wndclass);
+    if (!atom) {
+      PLOG(ERROR) << "RegisterClass";
+      return;
+    }
+
+    window_ = CreateWindow(MAKEINTATOM(atom),  // lpClassName
+                           nullptr,  // lpWindowName
+                           0,  // dwStyle
+                           0,  // x
+                           0,  // y
+                           0,  // nWidth
+                           0,  // nHeight
+                           nullptr,  // hWndParent
+                           nullptr,  // hMenu
+                           nullptr,  // hInstance
+                           this);  // lpParam
+    if (!window_) {
+      PLOG(ERROR) << "CreateWindow";
+      return;
+    }
+  }
+
+  MSG message;
+  BOOL rv = 0;
+  while (window_ && (rv = GetMessage(&message, window_, 0, 0)) > 0) {
+    TranslateMessage(&message);
+    DispatchMessage(&message);
+  }
+  if (window_ && rv == -1) {
+    PLOG(ERROR) << "GetMessage";
+    return;
+  }
+}
+
+// static
+LRESULT CALLBACK SessionEndWatcher::WindowProc(HWND window,
+                                               UINT message,
+                                               WPARAM w_param,
+                                               LPARAM l_param) {
+  // Figure out which object this is. A pointer to it is stuffed into the last
+  // parameter of CreateWindow(), which shows up as CREATESTRUCT::lpCreateParams
+  // in a WM_CREATE message. That should be processed before any of the other
+  // messages of interest to this function. Once the object is known, save a
+  // pointer to it in the GWLP_USERDATA slot for later retrieval when processing
+  // other messages.
+  SessionEndWatcher* self;
+  if (!GetWindowLongPtrAndSuccess(
+          window, GWLP_USERDATA, reinterpret_cast<LONG_PTR*>(&self))) {
+    PLOG(ERROR) << "GetWindowLongPtr";
+  }
+  if (!self && message == WM_CREATE) {
+    CREATESTRUCT* create = reinterpret_cast<CREATESTRUCT*>(l_param);
+    self = reinterpret_cast<SessionEndWatcher*>(create->lpCreateParams);
+    if (!SetWindowLongPtrAndGetSuccess(
+            window, GWLP_USERDATA, reinterpret_cast<LONG_PTR>(self))) {
+      PLOG(ERROR) << "SetWindowLongPtr";
+    }
+  }
+
+  if (self) {
+    if (message == WM_ENDSESSION) {
+      // If w_param is false, this WM_ENDSESSION message cancels a previous
+      // WM_QUERYENDSESSION.
+      if (w_param) {
+        self->SessionEnding();
+
+        // If the session is ending, post a close message which will kick off
+        // window destruction and cause the message loop thread to terminate.
+        if (!PostMessage(self->window_, WM_CLOSE, 0, 0)) {
+          PLOG(ERROR) << "PostMessage";
+        }
+      }
+    } else if (message == WM_DESTROY) {
+      // The window is being destroyed. Clear GWLP_USERDATA so that |self| won’t
+      // be found during a subsequent call into this function for this window.
+      // Clear self->window_ too, because it refers to an object that soon won’t
+      // exist. That signals the message loop to stop processing messages.
+      if (!SetWindowLongPtrAndGetSuccess(window, GWLP_USERDATA, 0)) {
+        PLOG(ERROR) << "SetWindowLongPtr";
+      }
+      self->window_ = nullptr;
+    }
+  }
+
+  // If the message is WM_CLOSE, DefWindowProc() will call DestroyWindow(), and
+  // this function will be called again with a WM_DESTROY message.
+  return DefWindowProc(window, message, w_param, l_param);
+}
+
+}  // namespace crashpad
diff --git a/util/win/session_end_watcher.h b/util/win/session_end_watcher.h
new file mode 100644
index 00000000..b23d391d
--- /dev/null
+++ b/util/win/session_end_watcher.h
@@ -0,0 +1,79 @@
+// Copyright 2017 The Crashpad Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef CRASHPAD_UTIL_WIN_SESSION_END_WATCHER_H_
+#define CRASHPAD_UTIL_WIN_SESSION_END_WATCHER_H_
+
+#include <windows.h>
+
+#include "base/macros.h"
+#include "util/thread/thread.h"
+#include "util/win/scoped_handle.h"
+
+namespace crashpad {
+
+//! \brief Creates a hidden window and waits for a `WM_ENDSESSION` message,
+//!     indicating that the session is ending and the application should
+//!     terminate.
+//!
+//! A dedicated thread will be created to run the `GetMessage()`-based message
+//! loop required to monitor for this message.
+//!
+//! Users should subclass this class and receive notifications by implementing
+//! the SessionEndWatcherEvent() method.
+class SessionEndWatcher : public Thread {
+ public:
+  SessionEndWatcher();
+
+  //! \note The destructor waits for the thread that runs the message loop to
+  //!     terminate.
+  ~SessionEndWatcher() override;
+
+ protected:
+  // Exposed for testing.
+  HWND GetWindow() const { return window_; }
+
+  // Exposed for testing. Blocks until window_ has been created. May be called
+  // multiple times if necessary.
+  void WaitForStart();
+
+  // Exposed for testing. Blocks until the message loop ends. May be called
+  // multiple times if necessary.
+  void WaitForStop();
+
+ private:
+  // Thread:
+  void ThreadMain() override;
+
+  static LRESULT CALLBACK WindowProc(HWND window,
+                                     UINT message,
+                                     WPARAM w_param,
+                                     LPARAM l_param);
+
+  //! \brief A `WM_ENDSESSION` message was received and it indicates that the
+  //!     user session will be ending imminently.
+  //!
+  //! This method is called on the thread that runs the message loop.
+  virtual void SessionEnding() = 0;
+
+  HWND window_;  // Conceptually strong, but ownership managed in ThreadMain()
+  ScopedKernelHANDLE started_;
+  ScopedKernelHANDLE stopped_;
+
+  DISALLOW_COPY_AND_ASSIGN(SessionEndWatcher);
+};
+
+}  // namespace crashpad
+
+#endif  // CRASHPAD_UTIL_WIN_SESSION_END_WATCHER_H_
diff --git a/util/win/session_end_watcher_test.cc b/util/win/session_end_watcher_test.cc
new file mode 100644
index 00000000..692d76e3
--- /dev/null
+++ b/util/win/session_end_watcher_test.cc
@@ -0,0 +1,62 @@
+// Copyright 2017 The Crashpad Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "util/win/session_end_watcher.h"
+
+#include "gtest/gtest.h"
+#include "test/errors.h"
+
+namespace crashpad {
+namespace test {
+namespace {
+
+class SessionEndWatcherTest final : public SessionEndWatcher {
+ public:
+  SessionEndWatcherTest() : SessionEndWatcher(), called_(false) {}
+
+  ~SessionEndWatcherTest() override {}
+
+  void Run() {
+    WaitForStart();
+
+    HWND window = GetWindow();
+    ASSERT_TRUE(window);
+    EXPECT_TRUE(PostMessage(window, WM_ENDSESSION, 1, 0));
+
+    WaitForStop();
+
+    EXPECT_TRUE(called_);
+  }
+
+ private:
+  // SessionEndWatcher:
+  void SessionEnding() override { called_ = true; }
+
+  bool called_;
+
+  DISALLOW_COPY_AND_ASSIGN(SessionEndWatcherTest);
+};
+
+TEST(SessionEndWatcher, SessionEndWatcher) {
+  SessionEndWatcherTest test;
+  test.Run();
+}
+
+TEST(SessionEndWatcher, DoNothing) {
+  SessionEndWatcherTest test;
+}
+
+}  // namespace
+}  // namespace test
+}  // namespace crashpad