Fixes regression introduced in fixing 19597. This change effectively

reverts menu_button to what it was before the fix. This way 19597 is
still fixed, and we don't have this crash. I'm working on a
regression test for coverage of this, but I don't want to hold up
anything with the fix. 

BUG=26279
TEST=see bug

Review URL: http://codereview.chromium.org/344043

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@30651 0039d316-1c4b-4281-b951-d872f2087c98