Propagate MediaStreamSource state to video tracks the same way as audio.

Also removes unused track states kLive and kFailed.
Since this also required a Video source to exist in all unit tests that create a track, a FakeVideoTrackSource is added and used in tests.

BUG=webrtc:5426

Review URL: https://codereview.webrtc.org/1790633002

Cr-Commit-Position: refs/heads/master@{#12098}

webrtc/api/java/src/org/webrtc/MediaStreamTrack.java

@@ -13,9 +13,7 @@ package org.webrtc;
 /** Java wrapper for a C++ MediaStreamTrackInterface. */
 public class MediaStreamTrack {
   /** Tracks MediaStreamTrackInterface.TrackState */
-  public enum State {
-    INITIALIZING, LIVE, ENDED, FAILED
-  }
+  public enum State { LIVE, ENDED }
 
   final long nativeTrack;