The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/f81152dc1ccfd10601766bfc2431c73bdcd94dce

commit f81152dc1ccfd10601766bfc2431c73bdcd94dce
Author: Greg Kraynov <kraynov@chromium.org>
Date: Tue Mar 06 17:34:34 2018

Blink Scheduler: Trace frame URLs.

It's especially useful for debugging cross-origin frame scheduling.
It also introduces StateTracer class which eventually simplified
tracing helper and further cleanup is to be done in the next CL.

Bug: 784439
Change-Id: I59512be41e6a13c27c6459738b54bbe1a10de6d2
Reviewed-on: https://chromium-review.googlesource.com/934441
Commit-Queue: Greg Kraynov <kraynov@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Alexander Timin <altimin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#541136}
[modify] https://crrev.com/f81152dc1ccfd10601766bfc2431c73bdcd94dce/third_party/WebKit/Source/core/frame/LocalFrameView.cpp
[modify] https://crrev.com/f81152dc1ccfd10601766bfc2431c73bdcd94dce/third_party/WebKit/Source/core/loader/EmptyClients.cpp
[modify] https://crrev.com/f81152dc1ccfd10601766bfc2431c73bdcd94dce/third_party/WebKit/Source/platform/WebFrameScheduler.h
[modify] https://crrev.com/f81152dc1ccfd10601766bfc2431c73bdcd94dce/third_party/WebKit/Source/platform/scheduler/renderer/web_frame_scheduler_impl.cc
[modify] https://crrev.com/f81152dc1ccfd10601766bfc2431c73bdcd94dce/third_party/WebKit/Source/platform/scheduler/renderer/web_frame_scheduler_impl.h
[modify] https://crrev.com/f81152dc1ccfd10601766bfc2431c73bdcd94dce/third_party/WebKit/Source/platform/scheduler/test/fake_web_frame_scheduler.h
[modify] https://crrev.com/f81152dc1ccfd10601766bfc2431c73bdcd94dce/third_party/WebKit/Source/platform/scheduler/util/tracing_helper.h