replace OVERRIDE and FINAL with override and final in chrome/browser/extensions/

replace OVERRIDE and FINAL with override and final in chrome/browser/extensions/

BUG=417463
Committed: https://crrev.com/a15bee143f21dcc0fb91b8b7f81848a7e51a38bb
Cr-Commit-Position: refs/heads/master@{#298134}

[Mostyn Bramley-Moore, 2014-10-03 22:21:02]

mostynb@opera.com changed reviewers:
+ dcheng@chromium.org, yoz@chromium.org

[Mostyn Bramley-Moore, 2014-10-03 22:22:04]

@yoz: here's another one of these OVERRIDE changes- can you give this a
thumbs-up?

[Yoyo Zhou, 2014-10-03 22:35:16]

On 2014/10/03 22:22:04, Mostyn Bramley-Moore wrote:
> @yoz: here's another one of these OVERRIDE changes- can you give this a
> thumbs-up?

LGTM

[Mostyn Bramley-Moore, 2014-10-03 22:37:14]

The CQ bit was checked by mostynb@opera.com

[commit-bot: I haz the power, 2014-10-03 22:39:19]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/624153002/1

[commit-bot: I haz the power, 2014-10-04 00:41:04]

Committed patchset #1 (id:1) as dc775c32f67918e7dffd3a801c7996d4b3828325

[commit-bot: I haz the power, 2014-10-04 00:41:30]

Patchset 1 (id:??) landed as
https://crrev.com/a15bee143f21dcc0fb91b8b7f81848a7e51a38bb
Cr-Commit-Position: refs/heads/master@{#298134}