UserAgent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/61.0.3163.100 Safari/537.36

Steps to reproduce the problem:
UserAgent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/61.0.3163.100 Safari/537.36

1. Have a Chrome instance in an active WebRTC session
2. Add a track to the remote browser (using the existing stream) and initiate a renegotiation

What is the expected behavior?
The new track should appear in the remote stream's track list (`pc.getRemoteStreams()[0]`)

What went wrong?
No new track is added to the remote stream, or it doesn't appear accessible in any way. The way I'm performing renegotiation works Chrome --> Firefox or Firefox <--> Firefox, but never when Chrome is on the receiving end of the new track.

Did this work before? Yes 60

Chrome version: 61.0.3163.100  Channel: stable
OS Version: 10.0
Flash Version: Shockwave Flash 27.0 r0

This is potentially related to #773613.

Chrome seems to be ignoring tracks associated with an SSRC identifier it has already seen. As a workaround, I am creating an entirely new stream to associate with the peer that contains the existing tracks and the newly added ones. 

I've attached SDP messages from two scenarios: The first case has the same stream used across renegotiations (and fails to create new tracks), and the other creates a new stream before renegotiating. SDP0 is from the initial negotiation where one audio track and one video track are present. In SDP1, a video track is added after having been removed since SDP0 (with ICE candidates omitted). I recommend running a diff of SDP0 and SDP1 for each of the cases to highlight exactly what's changed across the two scenarios.
 

Deleted: same-stream-sdp0.txt 3.2 KB

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Deleted: same-stream-sdp1.txt 3.2 KB

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Deleted: new-stream-sdp0.txt 3.2 KB

new-stream-sdp0.txt 3.2 KB View Download

Deleted: new-stream-sdp1.txt 3.2 KB

new-stream-sdp1.txt 3.2 KB View Download