[rAC, OSX] Make sure title shows.

The dialog got a non-constant title with the introduction of
ShouldShowSpinner(). This change ensures that a changed title is
updating the dialog.

BUG=277320

Review URL: https://codereview.chromium.org/25968002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226981 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226981