Potential fix for http://crbug.com/13111
Potential fix for http://crbug.com/13111

The browser_window_controller is destroyed before the window is destroyed.
In its dealloc, it sends the download shelf an |exiting| message that deletes
all item controllers, but the items's views might still be visible and hold
weak references to their controllers. When they are clicked, they would se
nd a message to free'd memory.

This is all speculation.

BUG=13111
TEST=Release to dev channel, monitor crash reports. Should go down.

Review URL: http://codereview.chromium.org/193109

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@26198 0039d316-1c4b-4281-b951-d872f2087c98

Crystalnix/house-of-life-chromium,Crystalnix/house-of-life-chromium,adobe/chromium,ropik/chromium,yitian134/chromium,Crystalnix/house-of-life-chromium,gavinp/chromium,adobe/chromium,Crystalnix/house-of-life-chromium,yitian134/chromium,adobe/chromium,ropik/chromium,Crystalnix/house-of-life-chromium,yitian134/chromium,adobe/chromium,yitian134/chromium,yitian134/chromium,ropik/chromium,gavinp/chromium,adobe/chromium,ropik/chromium,yitian134/chromium,adobe/chromium,ropik/chromium,yitian134/chromium,gavinp/chromium,Crystalnix/house-of-life-chromium,yitian134/chromium,yitian134/chromium,gavinp/chromium,gavinp/chromium,Crystalnix/house-of-life-chromium,ropik/chromium,adobe/chromium,adobe/chromium,ropik/chromium,Crystalnix/house-of-life-chromium,gavinp/chromium,gavinp/chromium,Crystalnix/house-of-life-chromium,gavinp/chromium,gavinp/chromium,adobe/chromium,yitian134/chromium,Crystalnix/house-of-life-chromium,adobe/chromium,ropik/chromium,Crystalnix/house-of-life-chromium,ropik/chromium,gavinp/chromium,adobe/chromium