Method onMouseDetected

src/input.js:132–137

* Registers an event handle in case if the mouse is detected. * @param {function(boolean)} handler * @param {boolean=} opt_fireImmediately * @return {!UnlistenDef}

(handler, opt_fireImmediately)

   * @return {!UnlistenDef}
   */
  onMouseDetected(handler, opt_fireImmediately) {
    if (opt_fireImmediately) {
      handler(this.isMouseDetected());
    }
    return this.mouseDetectedObservable_.add(handler);
  }

  /**
   * Whether the keyboard input is currently active.