This updates AppRTC to use addTrack instead of addStream, and removes the use of onAddStream, because we no longer have to wait for this to be fired to set the remote track's video renderers. Bug: webrtc:8869 Change-Id: I1ecae684a9bc4b30512e8c5d717e72b52c589831 Reviewed-on: https://webrtc-review.googlesource.com/57840 Commit-Queue: Seth Hampson <shampson@webrtc.org> Reviewed-by: Sami Kalliomäki <sakal@webrtc.org> Reviewed-by: Steve Anton <steveanton@webrtc.org> Cr-Commit-Position: refs/heads/master@{#22318}