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

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

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/7a69aba4fdece17645148f37ad2582174aa64c97
Cr-Commit-Position: refs/heads/master@{#326541}

[ncarter (slow), 2015-04-23 04:06:20]

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

[ncarter (slow), 2015-04-23 04:06:20]

maniscalco@ -- please review

[maniscalco, 2015-04-23 15:22:55]

lgtm

[ncarter (slow), 2015-04-23 16:34:47]

The CQ bit was checked by nick@chromium.org

[commit-bot: I haz the power, 2015-04-23 16:35:16]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1104543005/1

[commit-bot: I haz the power, 2015-04-23 16:39:25]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-23 16:40:16]

Patchset 1 (id:??) landed as
https://crrev.com/7a69aba4fdece17645148f37ad2582174aa64c97
Cr-Commit-Position: refs/heads/master@{#326541}