Roll ffmpeg DEPs for security fixes. Add regression tests.

Roll ffmpeg DEPs for security fixes. Add regression tests.

Pulls in the following fixes:
b9d631d avformat/utils: Clear pointer in ff_alloc_extradata() to avoid leaving a stale pointer in memory
7575fa1 avfilter/buffer: use av_freep() to avoid leaving stale pointers in memory
0aa6981 avformat/matroskadec: Use av_freep() to avoid leaving stale pointers in memory
e860c4c avformat/mov: use av_freep() to avoid leaving stale pointers in memory
c61fcd2 avformat/mov: Clear array to prevent potential out of array read from av_dlog()
a6dd29c avformat/mov: fix integer overflow in mov_read_udta_string()
878627f mov: Fix negative size calculation in mov_read_default().
c179d68 mov: Fix overflow and error handling in read_tfra().

BUG=444533, 444522, 444539, 444546
TEST=regression tests, test cases no longer crash
TBR=scherkus

Committed: https://crrev.com/d6cc2ec3bf2acdcb364fda90374158641b4e73be
Cr-Commit-Position: refs/heads/master@{#310173}

[DaleCurtis, 2015-01-06 21:03:56]

dalecurtis@chromium.org changed reviewers:
+ scherkus@chromium.org

[DaleCurtis, 2015-01-06 21:04:19]

The CQ bit was checked by dalecurtis@chromium.org

[commit-bot: I haz the power, 2015-01-06 21:04:54]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/838653002/1

[commit-bot: I haz the power, 2015-01-06 22:40:20]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-01-06 22:40:21]

Try jobs failed on following builders:
  mac_chromium_rel_ng on tryserver.chromium.mac
(http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_rel_...)

[DaleCurtis, 2015-01-06 22:46:12]

The CQ bit was checked by dalecurtis@chromium.org

[commit-bot: I haz the power, 2015-01-06 22:46:55]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/838653002/1

[commit-bot: I haz the power, 2015-01-06 23:42:59]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-01-06 23:43:58]

Patchset 1 (id:??) landed as
https://crrev.com/d6cc2ec3bf2acdcb364fda90374158641b4e73be
Cr-Commit-Position: refs/heads/master@{#310173}