Resolved Rebase Conflicts

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}

webrtc/modules/video_coding/main/source/receiver.h

@@ -28,6 +28,16 @@ class VCMReceiver {
   VCMReceiver(VCMTiming* timing,
               Clock* clock,
               EventFactory* event_factory);
+
+  // Using this constructor, you can specify a different event factory for the
+  // jitter buffer. Useful for unit tests when you want to simulate incoming
+  // packets, in which case the jitter buffer's wait event is different from
+  // that of VCMReceiver itself.
+  VCMReceiver(VCMTiming* timing,
+              Clock* clock,
+              rtc::scoped_ptr<EventWrapper> receiver_event,
+              rtc::scoped_ptr<EventWrapper> jitter_buffer_event);
+
   ~VCMReceiver();
 
   void Reset();