Merge "DO NOT MERGE - MPEG4Extractor: Check mLastTrack before dereferencing." into lmp-mr1-dev am: 622fd04e88 am: 862b281476  -s ours am: 5e94f64995 am: d7ec581644
am: 60d1b58bf1

Change-Id: I805902470bd4cc9432abbb7aa4192aa947176f38