Extract the code to produce a stream of frames to its own class,
FakeFrameSource. Use in VideoAdapter unittests, to make the code simpler
and not depend on the deprecated cricket::VideoCapturer.
Bug: webrtc:6353
Change-Id: Ib5c34c6a0bd7f4338650459873ddc94b12d0c569
Reviewed-on: https://webrtc-review.googlesource.com/49740
Commit-Queue: Niels Moller <nisse@webrtc.org>
Reviewed-by: Magnus Jedvert <magjed@webrtc.org>
Reviewed-by: Taylor Brandstetter <deadbeef@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#21995}
