[Picture-in-Picture] Add comments to PictureInPictureController

Bug: 806249
Change-Id: I18e6b7de189bbac3147c2d1c704aa911e49cd937
Reviewed-on: https://chromium-review.googlesource.com/897648
Commit-Queue: Mounir Lamouri <mlamouri@chromium.org>
Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
Reviewed-by: apacible <apacible@chromium.org>
Cr-Commit-Position: refs/heads/master@{#534990}
1 file changed