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
am: e67ec85275

* commit 'e67ec85275761fc2b8d55e3fb378528052b8fff7':
  DO NOT MERGE MPEG4Extractor: ensure kKeyTrackID exists before creating an MPEG4Source as track.

Change-Id: I96fd8075e4d3d379d30f7d269a47b15a1d3b4009