It is possible that due to model change the bookmark bubble window has been closed
but the popup is still showing and able to notify the controller of a folder change.
We ignore the sender in this case.

A better fix would be to close the popup programatically, but this is not a cocoa-friendly
thing to do.  I recommend this fix for M5, and for M6 we revisit to close the popup.

BUG=41257, 42766
TEST=Manual testing according to but report.  Requires two machines.  Will only crash under 10.6.

Review URL: http://codereview.chromium.org/1739015

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@45847 0039d316-1c4b-4281-b951-d872f2087c98