[Extensions Toolbar Mac] Make new toolbar actions slide out from the right

[Extensions Toolbar Mac] Make new toolbar actions slide out from the right

New extension button should slide out from the right, instead of the left.
Adjust the button's initial frame accordingly.

BUG=429810
Committed: https://crrev.com/a7f80b66a74e9d4be407e1a61c090e3946f6b161
Cr-Commit-Position: refs/heads/master@{#305062}

[Devlin, 2014-11-19 23:51:15]

rdevlin.cronin@chromium.org changed reviewers:
+ avi@chromium.org

[Devlin, 2014-11-19 23:51:15]

Two more super-small ones for you, Avi.

[Avi (use Gerrit), 2014-11-20 00:47:04]

lgtm

[Devlin, 2014-11-20 18:30:01]

The CQ bit was checked by rdevlin.cronin@chromium.org

[commit-bot: I haz the power, 2014-11-20 18:31:57]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/738223002/1

[commit-bot: I haz the power, 2014-11-20 19:38:07]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-11-20 19:38:59]

Patchset 1 (id:??) landed as
https://crrev.com/a7f80b66a74e9d4be407e1a61c090e3946f6b161
Cr-Commit-Position: refs/heads/master@{#305062}