The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/ce63450732e98d6e1341a97383dc7384cddac1f3

commit ce63450732e98d6e1341a97383dc7384cddac1f3
Author: johnme <johnme@chromium.org>
Date: Fri Jun 16 18:23:55 2017

[Media Controls] Add UMA for rotate-to-fullscreen feature

Measures how often rotate-to-fullscren enters or exits fullscreen:
- Media.Video.RotateToFullscreen.Enter
- Media.Video.RotateToFullscreen.Exit

and whether the screen orientation is allowed to rotate by the user:
- Media.Video.FullscreenOrientationLock.AutoRotateEnabled

BUG= 713703 

Review-Url: https://codereview.chromium.org/2936413002
Cr-Commit-Position: refs/heads/master@{#480105}

[modify] https://crrev.com/ce63450732e98d6e1341a97383dc7384cddac1f3/third_party/WebKit/Source/modules/media_controls/MediaControlsOrientationLockDelegate.cpp
[modify] https://crrev.com/ce63450732e98d6e1341a97383dc7384cddac1f3/third_party/WebKit/Source/modules/media_controls/MediaControlsRotateToFullscreenDelegate.cpp
[modify] https://crrev.com/ce63450732e98d6e1341a97383dc7384cddac1f3/tools/metrics/actions/actions.xml
[modify] https://crrev.com/ce63450732e98d6e1341a97383dc7384cddac1f3/tools/metrics/histograms/histograms.xml