The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/9347883f9cd91c1620297787c9b374ee0997e813

commit 9347883f9cd91c1620297787c9b374ee0997e813
Author: Josh Karlin <jkarlin@chromium.org>
Date: Fri Jan 11 15:40:10 2019

[AdsMetrics] Remove kAdsFeature and replace with kAdTagging

What: Replace kAdsFeature with kAdTagging

Why:
kAdsFeature was used to enable/disable ads metrics recording. Since
Ads Metrics now rely upon AdTagging to function and there isn't a
compelling need to enable/disable metrics independently of that, we
can remove it and just check for AdTagging.

Bug:  920594 
Change-Id: Ic36b4f2317e8a46d1187c38103314835dff141d4
Reviewed-on: https://chromium-review.googlesource.com/c/1404747
Commit-Queue: Josh Karlin <jkarlin@chromium.org>
Reviewed-by: Charlie Harrison <csharrison@chromium.org>
Cr-Commit-Position: refs/heads/master@{#622013}
[modify] https://crrev.com/9347883f9cd91c1620297787c9b374ee0997e813/chrome/browser/page_load_metrics/observers/ads_page_load_metrics_observer.cc
[modify] https://crrev.com/9347883f9cd91c1620297787c9b374ee0997e813/chrome/browser/page_load_metrics/observers/ads_page_load_metrics_observer_browsertest.cc
[modify] https://crrev.com/9347883f9cd91c1620297787c9b374ee0997e813/chrome/common/chrome_features.cc
[modify] https://crrev.com/9347883f9cd91c1620297787c9b374ee0997e813/chrome/common/chrome_features.h