[Picture-in-Picture] Add browser test for disablePictureInPicture.

This adds a browser test to check that setting disablePictureInPicture
on video just after requesting Picture-in-Picture doesn't result in a
window opened.

Bug: 806249
Change-Id: Idcc8c116f206a19ce3974c50ddff37b7bf2e8a50
Reviewed-on: https://chromium-review.googlesource.com/1092350
Commit-Queue: François Beaufort <beaufort.francois@gmail.com>
Reviewed-by: apacible <apacible@chromium.org>
Cr-Commit-Position: refs/heads/master@{#565781}
3 files changed