DO NOT MERGE - MPEG4Extractor: Check mLastTrack before dereferencing. am: 25d34cacde am: 428493c16d  -s ours am: c2af35e25d am: 4da47f34d9 am: 72d1936749 am: 203ce3a3e5  -s ours am: 26ffaaef5b
am: f6b9dcc895

Change-Id: I89e4ebd3c0ac193548115b21f9f007e247855245