Since SSRCs of RTP modules are now set at construction time, we can use just a simple unordered map from SSRC to module in packet router. Bug: webrtc:11036 Change-Id: I0b3527f17c9ee2df9253c778e5b9e3651a70b355 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/155965 Commit-Queue: Erik Språng <sprang@webrtc.org> Reviewed-by: Sebastian Jansson <srte@webrtc.org> Reviewed-by: Danil Chapovalov <danilchap@webrtc.org> Cr-Commit-Position: refs/heads/master@{#29510}