mac: Fix a nesting bug in http://crrev.com/87141

BUG=none
TEST=none
TBR=mark

Review URL: http://codereview.chromium.org/7087016

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@87148 0039d316-1c4b-4281-b951-d872f2087c98