DO NOT MERGE MPEG4Extractor: ensure kKeyTrackID exists before creating an MPEG4Source as track. am: b016207fc2 am: e2ca751723 am: 3d1df4f411  -s ours am: 1ed4ec584b  -s ours
am: 4223af4708

* commit '4223af4708e4524375385efe13f7ddebfd71ffcf':
  DO NOT MERGE MPEG4Extractor: ensure kKeyTrackID exists before creating an MPEG4Source as track.

Change-Id: I436f52467a51665718a613ef00ff8ad4899acd72