Move manifest_url_handler to //extensions

Move manifest_url_handler to //extensions

This moves extensions manifest URL handlers into //extensions
and renames the source files more appropriately to
"manifest_url_handlers"

Mechanical change, so all this noise is only header updates.

TBRs are for header changes only.

BUG=398671
[email protected] for app_mode change
[email protected] for themes change
[email protected] for ui changes

Committed: https://crrev.com/d5546141d24623e5653bbb1f1cc4aba831dcef0c
Cr-Commit-Position: refs/heads/master@{#299598}

[Ken Rockot(use gerrit already), 2014-10-14 21:39:43]

[email protected] changed reviewers:
+ [email protected]

[Ken Rockot(use gerrit already), 2014-10-14 21:39:44]

Vince could you please take a look?

[scheib, 2014-10-14 22:42:21]

lgtm

[Ken Rockot(use gerrit already), 2014-10-14 22:43:53]

The CQ bit was checked by [email protected]

[commit-bot: I haz the power, 2014-10-14 22:45:37]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/651353002/1

[commit-bot: I haz the power, 2014-10-14 22:55:46]

The CQ bit was unchecked by [email protected]

[commit-bot: I haz the power, 2014-10-14 22:55:48]

Try jobs failed on following builders:
  chromium_presubmit on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/chromium_presub...)

[Ken Rockot(use gerrit already), 2014-10-14 23:00:34]

The CQ bit was checked by [email protected]

[commit-bot: I haz the power, 2014-10-14 23:02:04]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/651353002/1

[commit-bot: I haz the power, 2014-10-15 00:29:16]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-10-15 00:30:47]

Patchset 1 (id:??) landed as
https://crrev.com/d5546141d24623e5653bbb1f1cc4aba831dcef0c
Cr-Commit-Position: refs/heads/master@{#299598}