The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/c89897f3128e194bf40ad1ee77b6085b0ddcd0d9

commit c89897f3128e194bf40ad1ee77b6085b0ddcd0d9
Author: Karan Bhatia <karandeepb@chromium.org>
Date: Thu Aug 10 01:06:40 2017

Distinguish between normal and extension renderers while recording thread load metrics.

The Blink Renderer Scheduler uses ThreadLoadTracker instances to measure main
thread load for backgrounded and foregrounded renderers. It's useful to measure
the same for extension renderer processes as well, to study how they contrast
with normal renderers. But currently, the content layer doesn't have the
information to determine if the current renderer process is an extension
renderer.

This CL plumbs this information through the RenderThread, which owns the
RendererScheduler. The renderer process type is passed as an enum to the
RendererScheduler, which logs UMA for the same.

BUG= 719102 

Change-Id: Ie288a7cab42f3605c829928cf298e23955db85ed
Reviewed-on: https://chromium-review.googlesource.com/590964
Reviewed-by: Camille Lamy <clamy@chromium.org>
Reviewed-by: Mark Pearson <mpearson@chromium.org>
Reviewed-by: Alexander Timin <altimin@chromium.org>
Reviewed-by: Jochen Eisinger <jochen@chromium.org>
Commit-Queue: Karan Bhatia <karandeepb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#493204}
[modify] https://crrev.com/c89897f3128e194bf40ad1ee77b6085b0ddcd0d9/chrome/renderer/chrome_content_renderer_client.cc
[modify] https://crrev.com/c89897f3128e194bf40ad1ee77b6085b0ddcd0d9/content/public/renderer/render_thread.h
[modify] https://crrev.com/c89897f3128e194bf40ad1ee77b6085b0ddcd0d9/content/public/test/mock_render_thread.cc
[modify] https://crrev.com/c89897f3128e194bf40ad1ee77b6085b0ddcd0d9/content/public/test/mock_render_thread.h
[modify] https://crrev.com/c89897f3128e194bf40ad1ee77b6085b0ddcd0d9/content/renderer/render_thread_impl.cc
[modify] https://crrev.com/c89897f3128e194bf40ad1ee77b6085b0ddcd0d9/content/renderer/render_thread_impl.h
[modify] https://crrev.com/c89897f3128e194bf40ad1ee77b6085b0ddcd0d9/third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc
[modify] https://crrev.com/c89897f3128e194bf40ad1ee77b6085b0ddcd0d9/third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.h
[modify] https://crrev.com/c89897f3128e194bf40ad1ee77b6085b0ddcd0d9/third_party/WebKit/Source/platform/scheduler/test/fake_renderer_scheduler.cc
[modify] https://crrev.com/c89897f3128e194bf40ad1ee77b6085b0ddcd0d9/third_party/WebKit/public/BUILD.gn
[modify] https://crrev.com/c89897f3128e194bf40ad1ee77b6085b0ddcd0d9/third_party/WebKit/public/platform/scheduler/renderer/renderer_scheduler.h
[add] https://crrev.com/c89897f3128e194bf40ad1ee77b6085b0ddcd0d9/third_party/WebKit/public/platform/scheduler/renderer_process_type.h
[modify] https://crrev.com/c89897f3128e194bf40ad1ee77b6085b0ddcd0d9/third_party/WebKit/public/platform/scheduler/test/fake_renderer_scheduler.h
[modify] https://crrev.com/c89897f3128e194bf40ad1ee77b6085b0ddcd0d9/third_party/WebKit/public/platform/scheduler/test/mock_renderer_scheduler.h
[modify] https://crrev.com/c89897f3128e194bf40ad1ee77b6085b0ddcd0d9/tools/metrics/histograms/histograms.xml