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

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

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=xiyuan@chromium.org

Committed: https://crrev.com/e099f7cfd7a940d60592bff5f3ebb6b6c9fe2a8a
Cr-Commit-Position: refs/heads/master@{#311760}

[xiyuan, 2015-01-15 21:15:32]

lgtm

[dcheng, 2015-01-15 21:16:38]

The CQ bit was checked by dcheng@chromium.org

[commit-bot: I haz the power, 2015-01-15 21:17:24]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/826743003/1

[commit-bot: I haz the power, 2015-01-15 22:53:00]

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

[commit-bot: I haz the power, 2015-01-15 22:53:01]

Try jobs failed on following builders:
  win_chromium_compile_dbg_ng on tryserver.chromium.win
(http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_comp...)

[dcheng, 2015-01-15 22:56:51]

The CQ bit was checked by dcheng@chromium.org

[commit-bot: I haz the power, 2015-01-15 22:58:30]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/826743003/1

[commit-bot: I haz the power, 2015-01-15 23:18:14]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-01-15 23:19:10]

Patchset 1 (id:??) landed as
https://crrev.com/e099f7cfd7a940d60592bff5f3ebb6b6c9fe2a8a
Cr-Commit-Position: refs/heads/master@{#311760}