The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/5503d4eec7c0bbcf26078e86f0236582e999c10d

commit 5503d4eec7c0bbcf26078e86f0236582e999c10d
Author: bmcquade <bmcquade@chromium.org>
Date: Thu Feb 16 19:23:19 2017

Refactor PageLoadExtraInfo::committed_url to url and did_commit fields.

Historically we exposed the start_url and committed_url to observers.
This makes it impossible to know the most recent URL in cases where a
page redirects but doesn't commit.

This patch fixes this. We now report the start_url and most recently known
URL, as well as a separate bit indicating whether the page committed.

This is needed for an upcoming UKM metrics tracking change where we
want to know the most recent URL in cases where a page load redirects but
fails to commit.

BUG= 692543 

Review-Url: https://codereview.chromium.org/2692373003
Cr-Commit-Position: refs/heads/master@{#451046}

[modify] https://crrev.com/5503d4eec7c0bbcf26078e86f0236582e999c10d/chrome/browser/page_load_metrics/metrics_web_contents_observer.cc
[modify] https://crrev.com/5503d4eec7c0bbcf26078e86f0236582e999c10d/chrome/browser/page_load_metrics/metrics_web_contents_observer_unittest.cc
[modify] https://crrev.com/5503d4eec7c0bbcf26078e86f0236582e999c10d/chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.cc
[modify] https://crrev.com/5503d4eec7c0bbcf26078e86f0236582e999c10d/chrome/browser/page_load_metrics/observers/data_reduction_proxy_metrics_observer.cc
[modify] https://crrev.com/5503d4eec7c0bbcf26078e86f0236582e999c10d/chrome/browser/page_load_metrics/observers/from_gws_page_load_metrics_observer.cc
[modify] https://crrev.com/5503d4eec7c0bbcf26078e86f0236582e999c10d/chrome/browser/page_load_metrics/observers/https_engagement_metrics/https_engagement_page_load_metrics_observer.cc
[modify] https://crrev.com/5503d4eec7c0bbcf26078e86f0236582e999c10d/chrome/browser/page_load_metrics/observers/service_worker_page_load_metrics_observer.cc
[modify] https://crrev.com/5503d4eec7c0bbcf26078e86f0236582e999c10d/chrome/browser/page_load_metrics/observers/subresource_filter_metrics_observer.cc
[modify] https://crrev.com/5503d4eec7c0bbcf26078e86f0236582e999c10d/chrome/browser/page_load_metrics/observers/ukm_page_load_metrics_observer.cc
[modify] https://crrev.com/5503d4eec7c0bbcf26078e86f0236582e999c10d/chrome/browser/page_load_metrics/page_load_metrics_observer.cc
[modify] https://crrev.com/5503d4eec7c0bbcf26078e86f0236582e999c10d/chrome/browser/page_load_metrics/page_load_metrics_observer.h
[modify] https://crrev.com/5503d4eec7c0bbcf26078e86f0236582e999c10d/chrome/browser/page_load_metrics/page_load_tracker.cc
[modify] https://crrev.com/5503d4eec7c0bbcf26078e86f0236582e999c10d/chrome/browser/page_load_metrics/page_load_tracker.h
[modify] https://crrev.com/5503d4eec7c0bbcf26078e86f0236582e999c10d/chrome/browser/prerender/prerender_browsertest.cc