The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/007281413c96597004125ba5d6b64fddc4a99dbe

commit 007281413c96597004125ba5d6b64fddc4a99dbe
Author: Tsuyoshi Horo <horo@chromium.org>
Date: Fri Jul 07 10:19:24 2017

Add SpecialApps UMAs of NavigationToParseStart for service worker controlled pages.

Bug:  738801 
Change-Id: I509dc0b19448bcd24752b11fc3fea8d7dc187808
Reviewed-on: https://chromium-review.googlesource.com/558728
Reviewed-by: Matt Falkenhagen <falken@chromium.org>
Reviewed-by: Mark Pearson <mpearson@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Commit-Queue: Tsuyoshi Horo <horo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#484875}
[modify] https://crrev.com/007281413c96597004125ba5d6b64fddc4a99dbe/chrome/browser/page_load_metrics/observers/service_worker_page_load_metrics_observer.cc
[modify] https://crrev.com/007281413c96597004125ba5d6b64fddc4a99dbe/chrome/browser/page_load_metrics/observers/service_worker_page_load_metrics_observer.h
[modify] https://crrev.com/007281413c96597004125ba5d6b64fddc4a99dbe/chrome/browser/page_load_metrics/observers/service_worker_page_load_metrics_observer_unittest.cc
[modify] https://crrev.com/007281413c96597004125ba5d6b64fddc4a99dbe/tools/metrics/histograms/histograms.xml