Limit mp4 atom size to something reasonable am: 638c99ba am: 569f3db6 am:...

Limit mp4 atom size to something reasonable am: 638c99ba am: 569f3db6 am: 29ccd8c5  -s ours am: 03bee198 am: 6c6dd8d9 am: e936431c am: fbd7146f am: e41bf03b am: 8b4b1cab am: 928bcad9 am: 548ad5e1 am: 130dbfb6 am: d5ec68c3
am: a6836b5e

Change-Id: I231349744418290ea1e4c5fc2b655889b2f08c2b