[Toolbar Mac UI] Simplify and correct omnibox pinning

[Toolbar Mac UI] Simplify and correct omnibox pinning

Fix a bug where the BrowserActionsContainerView would return the incorrect
resize delta x if it was changed while the user was resizing it (which could
happen during navigation).

Also fix a bug where actions were hidden if the toolbar redrew while the user
was resizing.

BUG=472821
Committed: https://crrev.com/05726c6d464e5cee4cd1bf387e454d14cbdcfa12
Cr-Commit-Position: refs/heads/master@{#323922}

[Devlin, 2015-04-03 19:56:49]

Patchset #1 (id:1) has been deleted

[Devlin, 2015-04-06 16:17:00]

Patchset #1 (id:20001) has been deleted

[Devlin, 2015-04-06 16:17:28]

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

[Devlin, 2015-04-06 16:17:29]

Avi, mind taking a look?

[Avi (use Gerrit), 2015-04-06 17:40:15]

lgtm

[Devlin, 2015-04-06 17:47:28]

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

[commit-bot: I haz the power, 2015-04-06 17:47:38]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1061623002/40001

[commit-bot: I haz the power, 2015-04-06 18:39:54]

Committed patchset #1 (id:40001)

[commit-bot: I haz the power, 2015-04-06 18:40:46]

Patchset 1 (id:??) landed as
https://crrev.com/05726c6d464e5cee4cd1bf387e454d14cbdcfa12
Cr-Commit-Position: refs/heads/master@{#323922}