Reason for revert:
Breaks some Call perf tests that are not run by the try bots....
Original issue's description:
> Fix bug in vie_encoder.cc which caused channel parameters not to be updated at regular intervals, as it was intended.
>
> That however exposes a bunch of failed test, so this CL also fixed a few other things:
> * FakeEncoder should trust the configured FPS value rather than guesstimating itself based on the realtime clock, so as not to completely undershoot targets in offline mode. Also, compensate for key-frame overshoots when outputting delta frames.
> * FrameDropper should not assuming incoming frame rate is 0 if no frames have been seen.
> * Fix a bunch of test cases that started failing because they were relying on the fake encoder undershooting.
> * Fix test
>
> BUG=7664
>
> Review-Url: https://codereview.webrtc.org/2883963002
> Cr-Commit-Position: refs/heads/master@{#18473}
> Committed: 6431e21da6TBR=stefan@webrtc.org,holmer@google.com
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=7664
Review-Url: https://codereview.webrtc.org/2923993002
Cr-Commit-Position: refs/heads/master@{#18475}
5390c4814d