Ash: Fix browser icon menu model lifetime

Ash: Fix browser icon menu model lifetime

The menu model needs to be cleaned up if the menu is suppressed for being
too short.

BUG=406609
TEST=manual, see bug

Committed: https://crrev.com/317db31b3a940b0835c97cf2fc561a7ea4085f1e
Cr-Commit-Position: refs/heads/master@{#291600}

[James Cook, 2014-08-22 22:32:17]

skuhne, PTAL

[Mr4D (OOO till 08-26), 2014-08-22 23:06:15]

I did do some digging and I think a bit more of a change is required here. See
comment. 
(but it simplifies the code :) )

https://codereview.chromium.org/486193004/diff/1/ash/shelf/shelf_view.cc
File ash/shelf/shelf_view.cc (right):

https://codereview.chromium.org/486193004/diff/1/ash/shelf/shelf_view.cc#newc...
ash/shelf/shelf_view.cc:1731: ui::GetMenuSourceTypeForEvent(event));
Looking at the code I am sure that you would need the same here.

Looking more I think that this code was because of some sub menu handling - but
there isn't a sub menu anymore.

As such: Upon return of ShowMenu the menu should be gone and the
|list_menu_model_| should be able to get deleted.

As such I would suggest to remove the |list_menu_model_| member and replace it
with a local incarnation of a scoped pointer deleting the model upon exiting of
this function.

I gave it a whirl (quick debugging) and as far as I can see it my assumption
should be correct.

[James Cook, 2014-08-22 23:18:30]

skuhne, PTAL

[Mr4D (OOO till 08-26), 2014-08-23 00:01:48]

lgtm

[James Cook, 2014-08-23 00:18:47]

The CQ bit was checked by jamescook@chromium.org

[commit-bot: I haz the power, 2014-08-23 04:56:21]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/jamescook@chromium.org/486193004/20001

[commit-bot: I haz the power, 2014-08-23 22:01:56]

Committed patchset #2 (20001) as 702acb39502448f886e9a0b21acae9002f94db84

[commit-bot: I haz the power, 2014-09-10 02:31:46]

Patchset 2 (id:??) landed as
https://crrev.com/317db31b3a940b0835c97cf2fc561a7ea4085f1e
Cr-Commit-Position: refs/heads/master@{#291600}