Move unlimitedStorage permission from //chrome to //extensions

Move unlimitedStorage permission from //chrome to //extensions

APIPermission::kUnlimitedStorage is used in the storage implementation in
//extensions so the permission should live there.

This allows app_shell to load apps with unlimitedStorage in the manifest.

BUG=none
TEST=existing browser_tests

Committed: https://crrev.com/54fb34b1d956047601edccd3638a1edea44d9b11
Cr-Commit-Position: refs/heads/master@{#308229}

[James Cook, 2014-12-12 23:46:13]

jamescook@chromium.org changed reviewers:
+ rockot@chromium.org

[James Cook, 2014-12-12 23:46:13]

Ken, PTAL

[Ken Rockot(use gerrit already), 2014-12-12 23:49:25]

lgtm - I actually just moved the permissions themselves in a recent CL and
forgot to move the permission features.

[James Cook, 2014-12-12 23:50:39]

The CQ bit was checked by jamescook@chromium.org

[commit-bot: I haz the power, 2014-12-12 23:52:16]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/805563002/1

[commit-bot: I haz the power, 2014-12-13 02:31:07]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-12-13 02:32:57]

Patchset 1 (id:??) landed as
https://crrev.com/54fb34b1d956047601edccd3638a1edea44d9b11
Cr-Commit-Position: refs/heads/master@{#308229}