code: function(event, releaseNotes, releaseName, releaseDate, updateURL) {
  			updateDownloaded = true;
  			logger.debug("update-downloaded: ", releaseName);
  			if (!updateDialog) {
  				electron.dialog.showMessageBox({
  					type: 'question',
  					message: 'Update version ' + releaseName + ' of ' + name + ' has been downloaded.',
  					detail: 'Would you like to restart the app and install the update? The update will be applied automatically upon closing.',
  					buttons: ['Update', 'Later']
  				}, function (response) {
  					if (response === 0) {
  						autoUpdater.quitAndInstall();
  					}
  				});
  				updateDialog = true;
  			}
  		}
docs: /* @callback