Fix a deleted memory read with the infobars

Some ui tests would crash when the browser was closed.
The problem was related to an infobar (the default browser one) showing.
When the tab is closed, InfoBarClosed is called on the infobar delegates, triggering a delete of the delegate. Then a notification that the tab is destroyed is sent, causing the tab contents to layout its infobars accessing the deleted delegates.

BUG=12668
TEST=All UI tests should pass (especially the LoginPromptTest ones).
     Make IE your default browser, start Chrome. The default browser infobar should show. Close the tab.


Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=17021

[Ben Goodger (Google), 2009-05-27 18:53:26]

OK