(defun change-to-wfoo-mode ()
  (interactive)
  (cond ((eq major-mode 'dired-mode)
         (wdired-change-to-wdired-mode))

        ((eq major-mode 'grep-mode)
         (wgrep-change-to-wgrep-mode))

        (t
         (message "Not in either dired-mode or grep-mode :("))))

(key-chord-define-global "ww" 'change-to-wfoo-mode)