This is just https://webrtc-codereview.appspot.com/53629004/ Remove a constructor of VCMJitterBuffer. Remove unnecessary factory use Comment Fix Move frame incoming simulation to the clock DCHECK typo fix Coding Style Fix Rephrased some comments, and removed some virtual for override function. Coding Style Fix Coding Style Fix Add a unittest for VCMReceiver::FrameForDecoding. Mainly test the time control algorithm. BUG= TBR=holmer@chromium.org Review URL: https://codereview.webrtc.org/1173253008. Cr-Commit-Position: refs/heads/master@{#9470}