Refreshed during triage.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d003ad1b523bb159524a253df3ad4245fdfbe1f0

commit d003ad1b523bb159524a253df3ad4245fdfbe1f0
Author: Ryan Sturm <ryansturm@chromium.org>
Date: Thu Mar 29 22:28:40 2018

Adding a page capping infobar and triggering logic

This CL introduces a page capping infobar, related strings, and
triggering logic from a page load metrics observer. The flow checks if a
feature is enabled and grabs parameters from a related field trial if
there are any. Once the data usage (of the body bytes for completed
requests) extends beyond a threshold, the infobar is triggerred. The
thresholds vary by whether the page load played media or not. This
does not yet introduce page pausing functionality. Although, the goal is
to pause all future requests from the page by plumbing a mojo message to
each related RenderFrame's scheduler.

Bug:  797980 ,  797976 
Change-Id: Ib6a48400c87f1561b10078f38c2d75d0c78ab912
Reviewed-on: https://chromium-review.googlesource.com/953711
Commit-Queue: Ryan Sturm <ryansturm@chromium.org>
Reviewed-by: Peter Kasting <pkasting@chromium.org>
Reviewed-by: Bryan McQuade <bmcquade@chromium.org>
Reviewed-by: Tarun Bansal <tbansal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#546986}
[modify] https://crrev.com/d003ad1b523bb159524a253df3ad4245fdfbe1f0/chrome/app/generated_resources.grd
[modify] https://crrev.com/d003ad1b523bb159524a253df3ad4245fdfbe1f0/chrome/browser/BUILD.gn
[modify] https://crrev.com/d003ad1b523bb159524a253df3ad4245fdfbe1f0/chrome/browser/data_use_measurement/chrome_data_use_ascriber.cc
[modify] https://crrev.com/d003ad1b523bb159524a253df3ad4245fdfbe1f0/chrome/browser/data_use_measurement/chrome_data_use_ascriber_unittest.cc
[add] https://crrev.com/d003ad1b523bb159524a253df3ad4245fdfbe1f0/chrome/browser/data_use_measurement/page_load_capping/page_load_capping_infobar_delegate.cc
[add] https://crrev.com/d003ad1b523bb159524a253df3ad4245fdfbe1f0/chrome/browser/data_use_measurement/page_load_capping/page_load_capping_infobar_delegate.h
[add] https://crrev.com/d003ad1b523bb159524a253df3ad4245fdfbe1f0/chrome/browser/data_use_measurement/page_load_capping/page_load_capping_infobar_delegate_unittest.cc
[delete] https://crrev.com/4df0bfb94bdc23558dcfb01ee2a4653db736e9df/chrome/browser/data_use_measurement/page_load_capping/page_load_observer.cc
[delete] https://crrev.com/4df0bfb94bdc23558dcfb01ee2a4653db736e9df/chrome/browser/data_use_measurement/page_load_capping/page_load_observer.h
[modify] https://crrev.com/d003ad1b523bb159524a253df3ad4245fdfbe1f0/chrome/browser/infobars/infobar_service.h
[modify] https://crrev.com/d003ad1b523bb159524a253df3ad4245fdfbe1f0/chrome/browser/infobars/infobars_browsertest.cc
[add] https://crrev.com/d003ad1b523bb159524a253df3ad4245fdfbe1f0/chrome/browser/infobars/mock_infobar_service.cc
[add] https://crrev.com/d003ad1b523bb159524a253df3ad4245fdfbe1f0/chrome/browser/infobars/mock_infobar_service.h
[add] https://crrev.com/d003ad1b523bb159524a253df3ad4245fdfbe1f0/chrome/browser/page_load_metrics/observers/page_capping_page_load_metrics_observer.cc
[add] https://crrev.com/d003ad1b523bb159524a253df3ad4245fdfbe1f0/chrome/browser/page_load_metrics/observers/page_capping_page_load_metrics_observer.h
[add] https://crrev.com/d003ad1b523bb159524a253df3ad4245fdfbe1f0/chrome/browser/page_load_metrics/observers/page_capping_page_load_metrics_observer_unittest.cc
[modify] https://crrev.com/d003ad1b523bb159524a253df3ad4245fdfbe1f0/chrome/browser/page_load_metrics/page_load_metrics_initialize.cc
[modify] https://crrev.com/d003ad1b523bb159524a253df3ad4245fdfbe1f0/chrome/test/BUILD.gn
[modify] https://crrev.com/d003ad1b523bb159524a253df3ad4245fdfbe1f0/components/infobars/core/infobar_delegate.h
[modify] https://crrev.com/d003ad1b523bb159524a253df3ad4245fdfbe1f0/tools/metrics/histograms/enums.xml