This is a reland of 17608dc4592fe25c1effdd75bf856f4af251942e Downstream fixed, relanding. Original change's description: > RtpRtcp modules and below: Make media, RTX and FEC SSRCs const > > Downstream usage of SetSsrc() / SetRtxSsrc() should now be gone. Let's > remove them, make the members const, and remove now unnecessary locking. > > Bug: webrtc:10774 > Change-Id: Ie4c1b3935508cf329c5553030f740c565d32e04b > Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/155660 > Commit-Queue: Erik Språng <sprang@webrtc.org> > Reviewed-by: Niels Moller <nisse@webrtc.org> > Cr-Commit-Position: refs/heads/master@{#29475} TBR=nisse@webrtc.org Bug: webrtc:10774 Change-Id: I759bed3ff1909857696c6d1b13df595a5e552f03 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/157049 Reviewed-by: Erik Språng <sprang@webrtc.org> Commit-Queue: Erik Språng <sprang@webrtc.org> Cr-Commit-Position: refs/heads/master@{#29486}