commit cfb35dd20e4dbab24f638e389ef17cc94f3a6da2
author Justin Novosad <junov@chromium.org> Mon Jun 05 20:33:18 2017
committer Commit Bot <commit-bot@chromium.org> Tue Jun 06 15:44:20 2017
tree a8bfb3393b42dd84f2bf5ca8dd9e0e95bd7c8745
parent c0d8b6b6430f423d3713df200ff40f8f5906e000

Halt OffscreenCanvas animations when page is hidden

This CL uses a (possibly) cross-thread asynchronous signal to notify
OffscreenCanvasFrameDispatcherImpl that it's associated placeholder
canvas has changed its visibility state.  This information is in turn
used to suspend animation in the OffscreenCanvas.

TBR=haraken@chromium.org

Bug: 715757
Change-Id: Ib41a76585a8a3fdc79ca43cf30b6229d3015807d
Reviewed-on: https://chromium-review.googlesource.com/523664
Commit-Queue: Justin Novosad <junov@chromium.org>
Reviewed-by: Xida Chen <xidachen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#477297}