This is to allow downstream cases to be able to set the media_has_been_sent flag in the sender as it's being removed from RtpState. Bug: webrtc:11581 Change-Id: I28f5fca96ba1d3f562c4d069d1b6d9af4002aaab Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/177524 Reviewed-by: Danil Chapovalov <danilchap@webrtc.org> Commit-Queue: Tommi <tommi@webrtc.org> Cr-Commit-Position: refs/heads/master@{#31545}