eb45981165
If a MediaStream is added to a PeerConnection, and later a track is added to the MediaStream, a new RtpSender will now be created for that track, and it will appear in subsequent offers. Similarly, removed tracks will remove RtpSenders. BUG=webrtc:5265 Review URL: https://codereview.webrtc.org/1507973003 Cr-Commit-Position: refs/heads/master@{#11040}