Reason for revert:
Breaks Vice tests
Original issue's description:
> Refactored incoming bitrate estimator.
>
> BUG=webrtc:7746
>
> Review-Url: https://codereview.webrtc.org/2917873002
> Cr-Commit-Position: refs/heads/master@{#18478}
> Committed: 5fc8bf8b87
TBR=philipel@webrtc.org,terelius@webrtc.org,stefan@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=webrtc:7746
Review-Url: https://codereview.webrtc.org/2924243002
Cr-Commit-Position: refs/heads/master@{#18486}