CL https://chromium-review.googlesource.com/c/chromium/src/+/1191745 is suspected of causing flakes in TracingSampleProfilerTest.JoinRunningTracing. Assigning to etienneb@, will likely revert.

This was auto-reverted by FindIt:
https://chromium-review.googlesource.com/c/chromium/src/+/1204918

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/bc88b69252221cbf250d804f9d997caf1e536f49

commit bc88b69252221cbf250d804f9d997caf1e536f49
Author: Findit <findit-for-me@appspot.gserviceaccount.com>
Date: Tue Sep 04 19:58:03 2018

Revert "Add a sampling profiler to chrome tracing."

This reverts commit 0ea3570a2882d86f47bf2cebf3e85a9fa16cd7a5.

Reason for revert:

Findit (https://goo.gl/kROfz5) identified CL at revision 588554 as the
culprit for flakes in the build cycles as shown on:
https://findit-for-me.appspot.com/waterfall/flake/flake-culprit?key=ag9zfmZpbmRpdC1mb3ItbWVyQwsSDEZsYWtlQ3VscHJpdCIxY2hyb21pdW0vMGVhMzU3MGEyODgyZDg2ZjQ3YmYyY2ViZjNlODVhOWZhMTZjZDdhNQw

Sample Failed Build: https://ci.chromium.org/buildbot/chromium.memory/Linux%20TSan%20Tests/25441

Sample Failed Step: components_unittests

Sample Flaky Test: TracingSampleProfilerTest.JoinRunningTracing

Original change's description:
> Add a sampling profiler to chrome tracing.
> 
> This CL is plumbing the base::StackProfiling to allow collecting
> stack sample at a low rate on the browser process.
> An event is triggered to the trace with the collected stackframe.
> 
> The goal of this code is to get low-rate stack samples in the field
> for the slow-report to help the investigation of stalled tasks.
> 
> 
> This is a variant of:
>   https://chromium-review.googlesource.com/c/chromium/src/+/1188502
> 
> R=ssid@chromium.org, oysteine@chromium.org
> 
> Change-Id: I150c17df51914f4535d4e7d6ec086a2e13c17cff
> Reviewed-on: https://chromium-review.googlesource.com/1191745
> Commit-Queue: Etienne Bergeron <etienneb@chromium.org>
> Reviewed-by: Mike Wittman <wittman@chromium.org>
> Reviewed-by: oysteine <oysteine@chromium.org>
> Reviewed-by: Alexei Filippov <alph@chromium.org>
> Reviewed-by: Siddhartha S <ssid@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#588554}

Change-Id: Ib5e99ed1b3270c811bdffc1495e806da9a66bb79
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug:  880526 
Reviewed-on: https://chromium-review.googlesource.com/1204918
Cr-Commit-Position: refs/heads/master@{#588627}
[modify] https://crrev.com/bc88b69252221cbf250d804f9d997caf1e536f49/base/trace_event/trace_log.cc
[modify] https://crrev.com/bc88b69252221cbf250d804f9d997caf1e536f49/chrome/browser/BUILD.gn
[modify] https://crrev.com/bc88b69252221cbf250d804f9d997caf1e536f49/chrome/browser/chrome_content_browser_client.cc
[delete] https://crrev.com/f2920dfe1c88deaf619a76c3189da7b331ca5957/chrome/browser/tracing/chrome_browser_main_extra_parts_tracing.cc
[delete] https://crrev.com/f2920dfe1c88deaf619a76c3189da7b331ca5957/chrome/browser/tracing/chrome_browser_main_extra_parts_tracing.h
[modify] https://crrev.com/bc88b69252221cbf250d804f9d997caf1e536f49/components/tracing/BUILD.gn
[delete] https://crrev.com/f2920dfe1c88deaf619a76c3189da7b331ca5957/components/tracing/common/tracing_sampler_profiler.cc
[delete] https://crrev.com/f2920dfe1c88deaf619a76c3189da7b331ca5957/components/tracing/common/tracing_sampler_profiler.h
[delete] https://crrev.com/f2920dfe1c88deaf619a76c3189da7b331ca5957/components/tracing/common/tracing_sampler_profiler_unittest.cc