c8f952deaa
Also removes unused track states kLive and kFailed. Since this also required a Video source to exist in all unit tests that create a track, a FakeVideoTrackSource is added and used in tests. BUG=webrtc:5426 Review URL: https://codereview.webrtc.org/1790633002 Cr-Commit-Position: refs/heads/master@{#12098}