code: function dirtyFileSaveCancelled() {
          UpdateInfoBar.showUpdateBar({
              type: "warning",
              title: Strings.WARNING_TYPE,
              description: Strings.UPDATE_ON_NEXT_LAUNCH
          });
      }
docs: Handles the Cancel button click by user in
  Unsaved changes prompt, which would come up if user
  has dirty files and he/she clicked UpdateNow