Update {virtual,override,final} to follow C++11 style in net, round 2.

Update {virtual,override,final} to follow C++11 style in net, round 2.

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
Committed: https://crrev.com/8ccc40cc9bf1d9bb5a83e7ac49a3802d665f12d3
Cr-Commit-Position: refs/heads/master@{#312739}

[dcheng, 2015-01-22 22:34:36]

dcheng@chromium.org changed reviewers:
+ eroman@chromium.org

[eroman, 2015-01-22 23:03:47]

lgtm

[dcheng, 2015-01-22 23:04:12]

The CQ bit was checked by dcheng@chromium.org

[commit-bot: I haz the power, 2015-01-22 23:05:21]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/867793002/1

[commit-bot: I haz the power, 2015-01-23 01:08:46]

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

[commit-bot: I haz the power, 2015-01-23 01:08:47]

Exceeded time limit waiting for builds to trigger.

[dcheng, 2015-01-23 01:14:45]

The CQ bit was checked by dcheng@chromium.org

[commit-bot: I haz the power, 2015-01-23 01:17:23]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/867793002/1

[commit-bot: I haz the power, 2015-01-23 01:48:27]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-01-23 01:49:45]

Patchset 1 (id:??) landed as
https://crrev.com/8ccc40cc9bf1d9bb5a83e7ac49a3802d665f12d3
Cr-Commit-Position: refs/heads/master@{#312739}