1) Add PtraceConnection which serves as the base class for specific
types of connections Crashpad uses to trace processes.
2) Add DirectPtraceConnection which is used when the handler process
has `ptrace` capabilities for the target process.
3) Move `ptrace` logic into Ptracer. This class isolates `ptrace` call
logic for use by various PtraceConnection implementations.
Bug: crashpad:30
Change-Id: I98083134a9f7d9f085e4cc816d2b85ffd6d73162
Reviewed-on: https://chromium-review.googlesource.com/671659
Commit-Queue: Joshua Peraza <jperaza@chromium.org>
Reviewed-by: Mark Mentovai <mark@chromium.org>
Reviewed-by: Leonard Mosescu <mosescu@chromium.org>
