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

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

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 an OS=android build using a
variation of https://codereview.chromium.org/598073004.

BUG=417463
R=torne@chromium.org

Committed: https://crrev.com/991d6faaf0dd6d37105f621783e0bc3d08be39e6
Cr-Commit-Position: refs/heads/master@{#314606}

[Torne, 2015-02-04 12:28:33]

lgtm

[dcheng, 2015-02-04 18:37:47]

The CQ bit was checked by dcheng@chromium.org

[commit-bot: I haz the power, 2015-02-04 18:38:38]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/882883007/1

[commit-bot: I haz the power, 2015-02-04 19:19:06]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-04 19:20:16]

Patchset 1 (id:??) landed as
https://crrev.com/991d6faaf0dd6d37105f621783e0bc3d08be39e6
Cr-Commit-Position: refs/heads/master@{#314606}