Linux: Pull a sysroot if pulling a local clang

Didn't actually end up being too bad. Also requires setting GN arg of

  target_sysroot = "//third_party/linux/sysroot"

when building.

Bug: crashpad:220
Change-Id: I4d4b282f165d454b5d32fc8cc11287ff665b943d
Reviewed-on: https://chromium-review.googlesource.com/935981
Commit-Queue: Scott Graham <scottmg@chromium.org>
Reviewed-by: Joshua Peraza <jperaza@chromium.org>

.gitignore

@@ -17,6 +17,7 @@
 /third_party/gtest/gtest
 /third_party/linux/.cipd
 /third_party/linux/clang
+/third_party/linux/sysroot
 /third_party/gyp/gyp
 /third_party/mini_chromium/mini_chromium
 /third_party/zlib/zlib

DEPS

@@ -134,6 +134,16 @@ hooks = [
       '-log-level', 'info',
     ],
   },
+  {
+    # If using a local clang ("pull_linux_clang" above), also pull down a
+    # sysroot.
+    'name': 'clang_linux',
+    'pattern': '.',
+    'condition': 'checkout_linux and pull_linux_clang',
+    'action': [
+      'crashpad/build/install_linux_sysroot.py',
+    ],
+  },
   {
     # Same rationale for using "install" rather than "ensure" as for first clang
     # package. https://crbug.com/789364.

build/install_linux_sysroot.py

@@ -0,0 +1,74 @@
+#!/usr/bin/env python
+
+# Copyright 2018 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.
+
+# Various code adapted from:
+# https://cs.chromium.org/chromium/src/build/linux/sysroot_scripts/install-sysroot.py
+
+import os
+import shutil
+import subprocess
+import sys
+import urllib2
+
+
+SCRIPT_DIR = os.path.dirname(os.path.abspath(__file__))
+
+# Sysroot revision from:
+# https://cs.chromium.org/chromium/src/build/linux/sysroot_scripts/sysroots.json
+SERVER = 'https://commondatastorage.googleapis.com'
+PATH = 'chrome-linux-sysroot/toolchain'
+REVISION = '3c248ba4290a5ad07085b7af07e6785bf1ae5b66'
+FILENAME = 'debian_stretch_amd64_sysroot.tar.xz'
+
+def main():
+  url = '%s/%s/%s/%s' % (SERVER, PATH, REVISION, FILENAME)
+
+  sysroot = os.path.join(SCRIPT_DIR, os.pardir,
+                         'third_party', 'linux', 'sysroot')
+
+  stamp = os.path.join(sysroot, '.stamp')
+  if os.path.exists(stamp):
+    with open(stamp) as s:
+      if s.read() == url:
+        return
+
+  print 'Installing Debian root image from %s' % url
+
+  if os.path.isdir(sysroot):
+    shutil.rmtree(sysroot)
+  os.mkdir(sysroot)
+  tarball = os.path.join(sysroot, FILENAME)
+  print 'Downloading %s' % url
+
+  for _ in range(3):
+    response = urllib2.urlopen(url)
+    with open(tarball, 'wb') as f:
+      f.write(response.read())
+    break
+  else:
+    raise Exception('Failed to download %s' % url)
+
+  subprocess.check_call(['tar', 'xf', tarball, '-C', sysroot])
+
+  os.remove(tarball)
+
+  with open(stamp, 'w') as s:
+    s.write(url)
+
+
+if __name__ == '__main__':
+  main()
+  sys.exit(0)