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

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

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 manually generated using a regex and a text editor.

BUG=417463
Committed: https://crrev.com/e3915ed9aeda4c38a8d391f7f41f127a790a762b
Cr-Commit-Position: refs/heads/master@{#326862}

[ncarter (slow), 2015-04-23 02:57:53]

nick@chromium.org changed reviewers:
+ wolenetz@chromium.org

[ncarter (slow), 2015-04-23 02:57:54]

wolentez: please review! thanks.

[ncarter (slow), 2015-04-24 16:15:09]

matt: ping :)

[wolenetz, 2015-04-24 18:16:54]

On 2015/04/24 16:15:09, ncarter wrote:
> matt: ping :)

On it now. I was TMCTWD'ing yesterday, sorry.

[wolenetz, 2015-04-24 18:30:22]

lgtm

[ncarter (slow), 2015-04-24 19:09:47]

The CQ bit was checked by nick@chromium.org

[commit-bot: I haz the power, 2015-04-24 19:11:07]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1102573006/1

[commit-bot: I haz the power, 2015-04-24 20:13:39]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-24 20:14:32]

Patchset 1 (id:??) landed as
https://crrev.com/e3915ed9aeda4c38a8d391f7f41f127a790a762b
Cr-Commit-Position: refs/heads/master@{#326862}