Avoid left shift of negative values when parsing H264 stream

Avoid left shift of negative values when parsing H264 stream

Emulation prevention three-byte detection only needs the previous
two bytes, so limit |prev_two_bytes_| to be just two bytes.

BUG=603485
TEST=test locally with clusterfuzz data

Committed: https://crrev.com/2112e70060f2f7f51fe594d02884703e74f1a582
Cr-Commit-Position: refs/heads/master@{#387505}

[jrummell, 2016-04-14 19:12:33]

jrummell@chromium.org changed reviewers:
+ sandersd@chromium.org

[jrummell, 2016-04-14 19:12:33]

PTAL.

[sandersd (OOO until July 31), 2016-04-14 19:14:25]

lgtm

[jrummell, 2016-04-14 22:04:01]

The CQ bit was checked by jrummell@chromium.org

[commit-bot: I haz the power, 2016-04-14 22:05:10]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1886423002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1886423002/1

[commit-bot: I haz the power, 2016-04-14 22:16:50]

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

[commit-bot: I haz the power, 2016-04-14 22:16:51]

Try jobs failed on following builders:
  cast_shell_linux on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/cast_shell_linu...)

[jrummell, 2016-04-14 23:43:08]

The CQ bit was checked by jrummell@chromium.org

[commit-bot: I haz the power, 2016-04-14 23:43:42]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1886423002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1886423002/1

[commit-bot: I haz the power, 2016-04-15 01:06:25]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-04-15 01:12:15]

Description was changed from

==========
Avoid left shift of negative values when parsing H264 stream

Emulation prevention three-byte detection only needs the previous
two bytes, so limit |prev_two_bytes_| to be just two bytes.

BUG=603485
TEST=test locally with clusterfuzz data
==========

to

==========
Avoid left shift of negative values when parsing H264 stream

Emulation prevention three-byte detection only needs the previous
two bytes, so limit |prev_two_bytes_| to be just two bytes.

BUG=603485
TEST=test locally with clusterfuzz data

Committed: https://crrev.com/2112e70060f2f7f51fe594d02884703e74f1a582
Cr-Commit-Position: refs/heads/master@{#387505}
==========

[commit-bot: I haz the power, 2016-04-15 01:12:16]

Patchset 1 (id:??) landed as
https://crrev.com/2112e70060f2f7f51fe594d02884703e74f1a582
Cr-Commit-Position: refs/heads/master@{#387505}