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

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

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/c3a924fd8ec1041f3320c6d784d98da681719d95
Cr-Commit-Position: refs/heads/master@{#326596}

[ncarter (slow), 2015-04-23 02:55:03]

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

[Nicolas Zea, 2015-04-23 17:05:18]

lgtm

[ncarter (slow), 2015-04-23 18:28:26]

The CQ bit was checked by nick@chromium.org

[commit-bot: I haz the power, 2015-04-23 18:29:03]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1063453006/1

[commit-bot: I haz the power, 2015-04-23 18:56:04]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-23 18:56:56]

Patchset 1 (id:??) landed as
https://crrev.com/c3a924fd8ec1041f3320c6d784d98da681719d95
Cr-Commit-Position: refs/heads/master@{#326596}