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

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

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/5120892497bc7707e492c045f1afebba3199a640
Cr-Commit-Position: refs/heads/master@{#326880}

[ncarter (slow), 2015-04-24 20:17:00]

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

[ncarter (slow), 2015-04-24 20:17:01]

Avi, please enjoy the bag of cotton candy that is this CL.

[Avi (use Gerrit), 2015-04-24 20:24:17]

lgtm

[cmumford, 2015-04-24 20:28:38]

On 2015/04/24 at 20:24:17, avi wrote:
> lgtm

"git cl format" has some nice fixups for this CL - you may want to consider
running that.

[ncarter (slow), 2015-04-24 21:11:15]

On 2015/04/24 20:28:38, cmumford wrote:
> On 2015/04/24 at 20:24:17, avi wrote:
> > lgtm
> 
> "git cl format" has some nice fixups for this CL - you may want to consider
> running that.

I know about git cl format :) In the case of this patch I rejected some of its
suggestions.

[ncarter (slow), 2015-04-24 21:11:25]

The CQ bit was checked by nick@chromium.org

[commit-bot: I haz the power, 2015-04-24 21:12:42]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1091093006/40001

[commit-bot: I haz the power, 2015-04-24 21:38:47]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2015-04-24 21:39:50]

Patchset 3 (id:??) landed as
https://crrev.com/5120892497bc7707e492c045f1afebba3199a640
Cr-Commit-Position: refs/heads/master@{#326880}