Update {virtual,override,final} to follow C++11 style in chrome/browser/chromeos/login.

Update {virtual,override,final} to follow C++11 style in chrome/browser/chromeos/login.

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
R=piman@chromium.org

Committed: https://crrev.com/ce340ea798bfd1b19700df5b82b56b1e96144369
Cr-Commit-Position: refs/heads/master@{#311790}

[piman, 2015-01-15 22:14:14]

lgtm

[dcheng, 2015-01-15 22:25:35]

The CQ bit was checked by dcheng@chromium.org

[commit-bot: I haz the power, 2015-01-15 22:54:31]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/856493004/1

[commit-bot: I haz the power, 2015-01-16 00:47:19]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-01-16 00:48:22]

Patchset 1 (id:??) landed as
https://crrev.com/ce340ea798bfd1b19700df5b82b56b1e96144369
Cr-Commit-Position: refs/heads/master@{#311790}