The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d28685525ed6cda7ee3cd9a84bca764d70512132

commit d28685525ed6cda7ee3cd9a84bca764d70512132
Author: bmcquade <bmcquade@chromium.org>
Date: Tue May 16 22:11:52 2017

Various cleaups for AMP page load metrics.

* add support for detecting URLs on the amp cache domain using the new
  host prefixing scheme

* add support for amp documents loaded in the google news viewer

* factor existing google url detection logic into a common helper, and use
  it in both amp observer and from search observer

* add metrics broken out by type of amp load (amp cache, google search viewer, etc)
  since performance may vary depending on view type (especially for bare amp cache
  urls)

BUG= 722690 

Review-Url: https://codereview.chromium.org/2880323003
Cr-Commit-Position: refs/heads/master@{#472226}

[modify] https://crrev.com/d28685525ed6cda7ee3cd9a84bca764d70512132/chrome/browser/page_load_metrics/observers/amp_page_load_metrics_observer.cc
[modify] https://crrev.com/d28685525ed6cda7ee3cd9a84bca764d70512132/chrome/browser/page_load_metrics/observers/amp_page_load_metrics_observer.h
[modify] https://crrev.com/d28685525ed6cda7ee3cd9a84bca764d70512132/chrome/browser/page_load_metrics/observers/amp_page_load_metrics_observer_unittest.cc
[modify] https://crrev.com/d28685525ed6cda7ee3cd9a84bca764d70512132/chrome/browser/page_load_metrics/observers/from_gws_page_load_metrics_observer.cc
[modify] https://crrev.com/d28685525ed6cda7ee3cd9a84bca764d70512132/chrome/browser/page_load_metrics/observers/from_gws_page_load_metrics_observer.h
[modify] https://crrev.com/d28685525ed6cda7ee3cd9a84bca764d70512132/chrome/browser/page_load_metrics/observers/from_gws_page_load_metrics_observer_unittest.cc
[modify] https://crrev.com/d28685525ed6cda7ee3cd9a84bca764d70512132/chrome/browser/page_load_metrics/page_load_metrics_util.cc
[modify] https://crrev.com/d28685525ed6cda7ee3cd9a84bca764d70512132/chrome/browser/page_load_metrics/page_load_metrics_util.h
[add] https://crrev.com/d28685525ed6cda7ee3cd9a84bca764d70512132/chrome/browser/page_load_metrics/page_load_metrics_util_unittest.cc
[modify] https://crrev.com/d28685525ed6cda7ee3cd9a84bca764d70512132/chrome/test/BUILD.gn
[modify] https://crrev.com/d28685525ed6cda7ee3cd9a84bca764d70512132/tools/metrics/histograms/histograms.xml

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/db2e320286b9752ed94f1bc6aa5e87eabe8eba6f

commit db2e320286b9752ed94f1bc6aa5e87eabe8eba6f
Author: bmcquade <bmcquade@chromium.org>
Date: Thu May 18 14:42:25 2017

Add support for counting same-document AMP loads.

Though we can't track timing metrics like FCP for same-document loads,
we can at least track how freqently they occur. This can help to
understand how significant the performance of non-same-document AMP
loads is, relative to the set of all AMP loads (both same doc and non
same doc).

BUG= 722690 

Review-Url: https://codereview.chromium.org/2888673002
Cr-Commit-Position: refs/heads/master@{#472802}

[modify] https://crrev.com/db2e320286b9752ed94f1bc6aa5e87eabe8eba6f/chrome/browser/page_load_metrics/metrics_web_contents_observer.cc
[modify] https://crrev.com/db2e320286b9752ed94f1bc6aa5e87eabe8eba6f/chrome/browser/page_load_metrics/observers/ads_page_load_metrics_observer.cc
[modify] https://crrev.com/db2e320286b9752ed94f1bc6aa5e87eabe8eba6f/chrome/browser/page_load_metrics/observers/ads_page_load_metrics_observer.h
[modify] https://crrev.com/db2e320286b9752ed94f1bc6aa5e87eabe8eba6f/chrome/browser/page_load_metrics/observers/amp_page_load_metrics_observer.cc
[modify] https://crrev.com/db2e320286b9752ed94f1bc6aa5e87eabe8eba6f/chrome/browser/page_load_metrics/observers/amp_page_load_metrics_observer.h
[modify] https://crrev.com/db2e320286b9752ed94f1bc6aa5e87eabe8eba6f/chrome/browser/page_load_metrics/observers/amp_page_load_metrics_observer_unittest.cc
[modify] https://crrev.com/db2e320286b9752ed94f1bc6aa5e87eabe8eba6f/chrome/browser/page_load_metrics/page_load_metrics_observer.cc
[modify] https://crrev.com/db2e320286b9752ed94f1bc6aa5e87eabe8eba6f/chrome/browser/page_load_metrics/page_load_metrics_observer.h
[modify] https://crrev.com/db2e320286b9752ed94f1bc6aa5e87eabe8eba6f/chrome/browser/page_load_metrics/page_load_tracker.cc
[modify] https://crrev.com/db2e320286b9752ed94f1bc6aa5e87eabe8eba6f/chrome/browser/page_load_metrics/page_load_tracker.h
[modify] https://crrev.com/db2e320286b9752ed94f1bc6aa5e87eabe8eba6f/tools/metrics/histograms/enums.xml
[modify] https://crrev.com/db2e320286b9752ed94f1bc6aa5e87eabe8eba6f/tools/metrics/histograms/histograms.xml