The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d02a1d189e60d72da5511ec2620a1ff89d642cf8

commit d02a1d189e60d72da5511ec2620a1ff89d642cf8
Author: ryansturm <ryansturm@chromium.org>
Date: Tue Mar 07 21:48:47 2017

Adding PLM UMA for byte usage by load type

Comparing various load types distribution of network vs cache usage will
give insights into how much data is really being used by these load
types. This will be useful to compare to existing TabRestore UMA as
well.

BUG= 695658 

Review-Url: https://codereview.chromium.org/2716903002
Cr-Commit-Position: refs/heads/master@{#455229}

[modify] https://crrev.com/d02a1d189e60d72da5511ec2620a1ff89d642cf8/chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.cc
[modify] https://crrev.com/d02a1d189e60d72da5511ec2620a1ff89d642cf8/chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.h
[modify] https://crrev.com/d02a1d189e60d72da5511ec2620a1ff89d642cf8/chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer_unittest.cc
[modify] https://crrev.com/d02a1d189e60d72da5511ec2620a1ff89d642cf8/tools/metrics/histograms/histograms.xml