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

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

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/d60f71748cc8d3fdfa30811b6896df6e4113d15a
Cr-Commit-Position: refs/heads/master@{#326544}

[ncarter (slow), 2015-04-23 14:05:50]

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

[ncarter (slow), 2015-04-23 14:05:51]

tsepez: please review! thanks.

[Tom Sepez, 2015-04-23 16:32:06]

On 2015/04/23 14:05:51, ncarter wrote:
> tsepez: please review! thanks.

LGTM.  Thanks for the cleanup.

[ncarter (slow), 2015-04-23 16:37:06]

The CQ bit was checked by nick@chromium.org

[commit-bot: I haz the power, 2015-04-23 16:38:06]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1084323007/1

[commit-bot: I haz the power, 2015-04-23 16:42:54]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-23 16:44:22]

Patchset 1 (id:??) landed as
https://crrev.com/d60f71748cc8d3fdfa30811b6896df6e4113d15a
Cr-Commit-Position: refs/heads/master@{#326544}