The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/23e36d51c9e144df205604b6fe7267f5a83f6266

commit 23e36d51c9e144df205604b6fe7267f5a83f6266
Author: Mounir Lamouri <mlamouri@chromium.org>
Date: Fri Apr 06 12:22:03 2018

Media Controls: use kMedia{Play,Pause}Button for overlay play button.

This is removing the kMediaOverlayPlayButton and resolves the issue of
exposing only the play state to the accessibility tools with the new
media controls.

Bug:  829579 
Change-Id: I4aa97ec6904933719bab02ef2451af0519230c03
Reviewed-on: https://chromium-review.googlesource.com/998553
Commit-Queue: Mounir Lamouri <mlamouri@chromium.org>
Reviewed-by: Becca Hughes <beccahughes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#548748}
[modify] https://crrev.com/23e36d51c9e144df205604b6fe7267f5a83f6266/third_party/WebKit/Source/modules/accessibility/AXMediaControls.cpp
[modify] https://crrev.com/23e36d51c9e144df205604b6fe7267f5a83f6266/third_party/WebKit/Source/modules/media_controls/elements/MediaControlElementType.h
[modify] https://crrev.com/23e36d51c9e144df205604b6fe7267f5a83f6266/third_party/WebKit/Source/modules/media_controls/elements/MediaControlOverlayPlayButtonElement.cpp