GitLab

Add an "autoplay" feature that controls autoplay and delegate
activation state through frames.

BUG=788390

TBR=skyostil@chromium.org,iclelland@chromium.org

Change-Id: I67e40ae00b0ca7acad7bbef4b4cb4525a9e65fb3
Reviewed-on: https://chromium-review.googlesource.com/800851
Commit-Queue: Becca Hughes <beccahughes@chromium.org>
Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
Cr-Commit-Position: refs/heads/master@{#520589}