fb2aceded6
With this, RtpSender and RtpReceiver will always return an SSRC if one is available. Also, attempts to change the SSRC with SetParameters will fail, rather than silently doing nothing. BUG=webrtc:6888 Review-Url: https://codereview.webrtc.org/2567333004 Cr-Commit-Position: refs/heads/master@{#15939}