Merge 101958 - Attempt at fixing crash in menus shown from infobars. Here's what the

Merge 101958 - Attempt at fixing crash in menus shown from infobars. Here's what the
current code does when closing an infobar:
. The animation ends, resulting in a delayed deletion of InfoBarView
  (InfoBarContainerView::PlatformSpecificRemoveInfoBar).
. The InfoBarDelegate deletes itself (InfoBarDelegate::InfoBarClosed).
. Eventually the InfoBarView is deleted.
This leaves a window of time between which the view is alive, but the
delegate has been deleted. The view doesn't directly reference the
delegate anymore, but the menu models created by the infobarviews
do. This means if a paint comes in to the menu it's going to query the
deleted delegate and we crash.

I made CancelMenu pure virtual in hopes of avoiding this in the future
by making subclasses think about it.

BUG=93314
TEST=make sure menus on infobars still work.
R=pkasting@chromium.org

Review URL: http://codereview.chromium.org/7796010

TBR=sky@chromium.org
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=102375