Method onTouchDetected

src/input.js:111–116

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

(handler, opt_fireImmediately)

   * @return {!UnlistenDef}
   */
  onTouchDetected(handler, opt_fireImmediately) {
    if (opt_fireImmediately) {
      handler(this.isTouchDetected());
    }
    return this.touchDetectedObservable_.add(handler);
  }

  /**
   * Whether the mouse input has been detected.