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

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

[Sending this chunk by itself since it's slightly less rote than the others]

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/b05b81d7617e11ae4612afc15aab69b6f57293fe
Cr-Commit-Position: refs/heads/master@{#326504}

[ncarter (slow), 2015-04-23 03:55:08]

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

[ncarter (slow), 2015-04-23 03:55:08]

bbudge: Please review -- I added some missing overrides here to non-dtor methods
in this file, so it's its own change.

[bbudge, 2015-04-23 13:30:51]

lgtm

[ncarter (slow), 2015-04-23 13:52:38]

The CQ bit was checked by nick@chromium.org

[commit-bot: I haz the power, 2015-04-23 13:53:00]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1100733003/1

[commit-bot: I haz the power, 2015-04-23 14:01:01]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-23 14:02:03]

Patchset 1 (id:??) landed as
https://crrev.com/b05b81d7617e11ae4612afc15aab69b6f57293fe
Cr-Commit-Position: refs/heads/master@{#326504}