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

Update {virtual,override} to follow C++11 style in 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 manually generated using a regex and a text editor.

BUG=417463
Committed: https://crrev.com/d3f30d02fb6e676e9a46776325e21f64903c201d
Cr-Commit-Position: refs/heads/master@{#326489}

[ncarter (slow), 2015-04-23 03:20:55]

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

[ncarter (slow), 2015-04-23 03:20:56]

rsleevi: Please review

[Ryan Sleevi, 2015-04-23 10:15:27]

lgtm

[Ryan Sleevi, 2015-04-23 10:15:33]

The CQ bit was checked by rsleevi@chromium.org

[commit-bot: I haz the power, 2015-04-23 10:15:47]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1088903008/20001

[commit-bot: I haz the power, 2015-04-23 10:18:46]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-04-23 10:19:50]

Patchset 2 (id:??) landed as
https://crrev.com/d3f30d02fb6e676e9a46776325e21f64903c201d
Cr-Commit-Position: refs/heads/master@{#326489}