[Picture-in-Picture] Add tests if video src is a MediaStream.

Following previous CL, this makes sure we have tests when
requestPictureInPicture promise rejects if video src is a MediaStream as
backend is not implemented yet.

Bug: 806249
Change-Id: I8c32f7de8ef9f5455a1909d83810edce76d35e2f
Reviewed-on: https://chromium-review.googlesource.com/1085062
Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
Commit-Queue: François Beaufort <beaufort.francois@gmail.com>
Cr-Commit-Position: refs/heads/master@{#564219}
1 file changed