[Picture-in-Picture] Show/hide window.

This CL makes sure that calling video.requestPictureInPicture() shows a
Picture-in-Picture window and that setting disablePictureInPicture to
true or calling document.exitPictureInPicture() hides the
Picture-in-Picture window.

Bug: 806249
Change-Id: Ifa9e6df55c913d6eb68fd0fbb59450d3d516ee1c
Reviewed-on: https://chromium-review.googlesource.com/1006956
Reviewed-by: apacible <apacible@chromium.org>
Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
Commit-Queue: François Beaufort <beaufort.francois@gmail.com>
Cr-Commit-Position: refs/heads/master@{#550572}
4 files changed