Update {virtual,override,final} to follow C++11 style in media, round 2.

Update {virtual,override,final} to follow C++11 style in media, round 2.

The Google style guide states that only one of {virtual,override,final}
should be used for each declaration, since override implies virtual and
final implies both virtual and override.

This patch was automatically generated with a ChromeOS build using a
variation of https://codereview.chromium.org/598073004.

BUG=417463
Committed: https://crrev.com/3c3e12faa0908b087303764d76bc99baa8e40183
Cr-Commit-Position: refs/heads/master@{#312798}

[dcheng, 2015-01-22 22:33:24]

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

[jrummell, 2015-01-23 00:22:46]

lgtm

[dcheng, 2015-01-23 00:25:06]

The CQ bit was checked by dcheng@chromium.org

[commit-bot: I haz the power, 2015-01-23 00:26:16]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/870743003/1

[commit-bot: I haz the power, 2015-01-23 02:29:17]

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

[commit-bot: I haz the power, 2015-01-23 02:29:18]

Exceeded time limit waiting for builds to trigger.

[dcheng, 2015-01-23 02:35:15]

The CQ bit was checked by dcheng@chromium.org

[commit-bot: I haz the power, 2015-01-23 02:36:19]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/870743003/1

[commit-bot: I haz the power, 2015-01-23 02:37:52]

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

[commit-bot: I haz the power, 2015-01-23 02:37:53]

Try jobs failed on following builders:
  win_gpu on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/win_gpu/builds/11...)

[dcheng, 2015-01-23 08:40:37]

The CQ bit was checked by dcheng@chromium.org

[commit-bot: I haz the power, 2015-01-23 08:41:16]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/870743003/1

[commit-bot: I haz the power, 2015-01-23 08:42:17]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-01-23 08:43:24]

Patchset 1 (id:??) landed as
https://crrev.com/3c3e12faa0908b087303764d76bc99baa8e40183
Cr-Commit-Position: refs/heads/master@{#312798}