code: function Notifications(chrome) {
    this.chrome = chrome;
    
    
    /**
     * Creates and displays a notification.
     * 
     * @param {string} notificationId 
     * @param {[object Object]} options 
     * @param {function} callback 
     */
    this.create = sinon.stub();
    
    /**
     * Updates an existing notification.
     * 
     * @param {string} notificationId 
     * @param {[object Object]} options 
     * @param {function} callback 
     */
    this.update = sinon.stub();
    
    /**
     * Clears the specified notification.
     * 
     * @param {string} notificationId 
     * @param {function} callback 
     */
    this.clear = sinon.stub();
    
    /**
     * Retrieves all the notifications.
     * 
     * @param {function} callback 
     */
    this.getAll = sinon.stub();
    
    /**
     * Retrieves whether the user has enabled notifications from this app or extension.
     * 
     * @param {function} callback 
     */
    this.getPermissionLevel = sinon.stub();
    
    
    /**
     */
    this.onClosed = new Event();
    
    /**
     */
    this.onClicked = new Event();
    
    /**
     */
    this.onButonClicked = new Event();
    
    /**
     */
    this.onPermissionLevelChanged = new Event();
    
    /**
     */
    this.onShowSettings = new Event();
    
  }
docs: Use the <code>chrome.notifications</code> API to create rich notifications using
  templates and show these notifications to users in the system tray.
  @constructor
  @param {object} chrome