ba29c6aac7
Relanding again after fixing issue with RTC_DCHECKs. This CL eliminates the need for the extra layer of indirection provided by mediastreamprovider.h. It will thus make it easier to implement new functionality in RtpSender/RtpReceiver. It also brings us one step closer to the end goal of combining "senders" and "send streams". Currently the sender still needs to go through the BaseChannel and MediaChannel, using an SSRC as a key. R=pthatcher@webrtc.org Review URL: https://codereview.webrtc.org/2046173002 . Cr-Commit-Position: refs/heads/master@{#13305}