This reverts commit ba97ba7af917d4152f5f3363aba1c1561c6673dc. Reason for revert: The new tests have caused several test failures on the test bots; the method FakeAudioMediaStreamTrack:GetSignalLevel, which is not supposed to be called is sometimes called anyway. Original change's description: > Added PeerConnectionObserver::OnRemoveTrack. > > This corresponds to processing the removal of a remote track step of > the spec, with processing the addition of a remote track already > covered by OnAddTrack. > https://w3c.github.io/webrtc-pc/#processing-remote-mediastreamtracks > > Bug: webrtc:8260, webrtc:8315 > Change-Id: Ica8be92369733eb3cf1397fb60385d45a9b58700 > Reviewed-on: https://webrtc-review.googlesource.com/4722 > Commit-Queue: Henrik Boström <hbos@webrtc.org> > Reviewed-by: Taylor Brandstetter <deadbeef@webrtc.org> > Reviewed-by: Steve Anton <steveanton@webrtc.org> > Cr-Commit-Position: refs/heads/master@{#20214} TBR=steveanton@webrtc.org,deadbeef@webrtc.org,hbos@webrtc.org Change-Id: Id2d9533e27227254769b4280a8ff10a47313e714 No-Presubmit: true No-Tree-Checks: true No-Try: true Bug: webrtc:8260, webrtc:8315 Reviewed-on: https://webrtc-review.googlesource.com/7940 Reviewed-by: Alex Loiko <aleloi@webrtc.org> Commit-Queue: Alex Loiko <aleloi@webrtc.org> Cr-Commit-Position: refs/heads/master@{#20218}