Consolidate ExtensionAction execution code

Combine methods to execute extension actions into one place
in ExtensionActionAPI. This also cleans up
ExtensionToolbarModel and PageActionController, since they
had too much knowledge about how to execute these actions.
We also get to consolidate code in views, since now executing
page and browser actions has a single API.

Woohoo for -100 lines of code!

BUG=406447
Committed: https://crrev.com/e9c71127d0d3bebe87ca105d557daf526f9d753c
Cr-Commit-Position: refs/heads/master@{#291790}

[Finnur, 2014-08-25 13:38:33]

A little hard to follow at times and would have been good to see a try run, but
LGTM.

I'll try adding a couple of bots, for good measure, so you'll have some results
when you show up.

[Devlin, 2014-08-25 17:04:03]

On 2014/08/25 13:38:33, Finnur wrote:
> A little hard to follow at times and would have been good to see a try run,
but
> LGTM.
> 
> I'll try adding a couple of bots, for good measure, so you'll have some
results
> when you show up.

Trybot runs were are all on PatchSet 1; sorry, should have mentioned that. 
Thanks for triggering the next set. :)

[Devlin, 2014-08-25 20:02:13]

+avi for cocoa/

[Avi (use Gerrit), 2014-08-25 20:14:46]

Cocoa stuff LGTM. Trusting that the extensiony stuff in the Cocoa stuff is fine;
I don't know that.

[Devlin, 2014-08-25 20:22:56]

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

[commit-bot: I haz the power, 2014-08-25 20:24:22]

CQ is trying da patch. Follow status at

https://chromium-status.appspot.com/cq/rdevlin.cronin@chromium.org/496863003/...

[commit-bot: I haz the power, 2014-08-25 21:30:45]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  mac_gpu_retina_triggered_tests on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/mac_gpu_retina_tr...)
  mac_chromium_rel_swarming on tryserver.chromium.mac
(http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_rel_...)

[commit-bot: I haz the power, 2014-08-25 22:39:07]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-08-25 22:39:08]

Try jobs failed on following builders:
  mac_chromium_rel_swarming on tryserver.chromium.mac
(http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_rel_...)

[Devlin, 2014-08-25 22:45:44]

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

[commit-bot: I haz the power, 2014-08-25 22:48:53]

CQ is trying da patch. Follow status at

https://chromium-status.appspot.com/cq/rdevlin.cronin@chromium.org/496863003/...

[commit-bot: I haz the power, 2014-08-25 23:48:04]

Committed patchset #3 (100001) as 9204a75e75ebbcb48f22c5badae361f07b3fc8aa

[commit-bot: I haz the power, 2014-09-10 02:38:39]

Patchset 3 (id:??) landed as
https://crrev.com/e9c71127d0d3bebe87ca105d557daf526f9d753c
Cr-Commit-Position: refs/heads/master@{#291790}