[Mac] Insert the Update Chrome item to existing Wrench menus when notified.

BUG=50659
TEST=Wait for upgrade. Get yellow ball on Wrench menu. Open menu, see Update Chrome item.

Review URL: http://codereview.chromium.org/3124002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@55568 0039d316-1c4b-4281-b951-d872f2087c98
3 files changed