trackjs怎么关闭摄像头

最近开发一个谷歌浏览器扩展,有需要用到人脸识别,因此使用了trackjs来实现这个功能,但是一直遇到问题是在调用trackerTask.stop();停止识别后,摄像头依然无法关闭;

trackerTask是什么?

trackerTask = tracking.track(‘#face_video_video’, tracker, { camera: true });

网上寻找多久后终于找到如下解决办法

在trackingjs源码中找到以下代码
  /**
   * Captures the user camera when tracking a video element and set its source
   * to the camera stream.
   * @param {HTMLVideoElement} element Canvas element to track.
   * @param {object} opt_options Optional configuration to the tracker.
   */
  tracking.initUserMedia_ = function(element, opt_options) {
    window.navigator.mediaDevices.getUserMedia({
      video: true,
      audio: (opt_options && opt_options.audio) ? true : false,
    }).then(function(stream) {
      element.srcObject = stream;
      window.stream = stream; //增加这一行,将元素的stream赋予到window
    }).catch(function(err) {
      throw Error('Cannot capture user camera.');
    });
  };

然后找到以下代码,包含开启摄像头的方法
  tracking.track = function(element, tracker, opt_options) {
    element = tracking.one(element);
    element.srcObject = window.stream; //加上这行
    if (!element) {
      throw new Error('Element not found, try a different element or selector.');
    }
    if (!tracker) {
      throw new Error('Tracker not specified, try `tracking.track(element, new tracking.FaceTracker())`.');
    }

    switch (element.nodeName.toLowerCase()) {
      case 'canvas':
        return this.trackCanvas_(element, tracker, opt_options);
      case 'img':
        return this.trackImg_(element, tracker, opt_options);
      case 'video':
        if (opt_options) {
          if (opt_options.camera) {
            this.initUserMedia_(element, opt_options);
          }
        }
        return this.trackVideo_(element, tracker, opt_options);
      default:
        throw new Error('Element not supported, try in a canvas, img, or video.');
    }
  };

然后关闭

            if (typeof window.stream === "object") { //关闭摄像头
                window.stream.getTracks().forEach(track => track.stop());
                document.getElementById("xxx").srcObject = null;
            }

xxx就是初始化track时候配置的video元素

但是，调用摄像头指示灯是关闭了,但在地址栏依然能看到当前网页正在使用,不知道究竟是关闭了还是没有关闭处于静默状态