That means it does not have to be set on every update of StreamsConfig. BUG=webrtc:9586 Change-Id: I6a348160e209042857c4475323466e2aa92adef8 Reviewed-on: https://webrtc-review.googlesource.com/c/116690 Reviewed-by: Sebastian Jansson <srte@webrtc.org> Commit-Queue: Per Kjellander <perkj@webrtc.org> Cr-Commit-Position: refs/heads/master@{#26184}