Reason for revert:
Problem was the rename of the include file. Intend to keep the old name for now, and then reland.
Original issue's description:
> Revert of Delete class MockCongestionController. (patchset #4 id:60001 of https://codereview.webrtc.org/2762023004/ )
>
> Reason for revert:
> This is breaking downstream build.
>
> Original issue's description:
> > Delete class MockCongestionController.
> >
> > It became unused in cl https://codereview.webrtc.org/2516983004.
> >
> > BUG=None
> >
> > Review-Url: https://codereview.webrtc.org/2762023004
> > Cr-Commit-Position: refs/heads/master@{#17325}
> > Committed: d19bcb7116
>
> TBR=stefan@webrtc.org,nisse@webrtc.org
> # Skipping CQ checks because original CL landed less than 1 days ago.
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=None
>
> Review-Url: https://codereview.webrtc.org/2762133003
> Cr-Commit-Position: refs/heads/master@{#17330}
> Committed: e27f1e764eTBR=stefan@webrtc.org,skvlad@webrtc.org
BUG=None
Review-Url: https://codereview.webrtc.org/2766133002
Cr-Commit-Position: refs/heads/master@{#17338}
40854eab23