Reason for revert:
Might be the root cause of an internal test failure.
Original issue's description:
> Verify sender ssrc when receiving rtcp target bitrate
>
> BUG=webrtc:8137
>
> Review-Url: https://codereview.webrtc.org/3000373002
> Cr-Commit-Position: refs/heads/master@{#19524}
> Committed: a7a4beb419TBR=danilchap@webrtc.org,sprang@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=webrtc:8137
Review-Url: https://codereview.webrtc.org/3005633002
Cr-Commit-Position: refs/heads/master@{#19529}