Roll FFmpeg DEPs for MP3 and MOV playback fixes.

Pulls in:
0ff816d avformat/mov: fix keyframe flags for sample from chromium Issue 340865
ff0501e avformat/mp3dec: optimize mp3_seek() for dir < 0

BUG=340865,346623
TEST=Files from both issues now playback.
TBR=scherkus

Review URL: https://codereview.chromium.org/185553011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@254793 0039d316-1c4b-4281-b951-d872f2087c98
Update .DEPS.git

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@254794 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 254794