chrome-extensions-samples/_archive/mv2/api/tabCapture/receiver.js

// Copyright 2016 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// Note: |window.currentStream| was set in background.js.

// Stop video play-out, stop the MediaStreamTracks, and set style class to
// "shutdown".
function shutdownReceiver() {
  if (!window.currentStream) {
    return;
  }

  var player = document.getElementById('player');
  player.srcObject = null;
  var tracks = window.currentStream.getTracks();
  for (var i = 0; i < tracks.length; ++i) {
    tracks[i].stop();
  }
  window.currentStream = null;

  document.body.className = 'shutdown';
}

window.addEventListener('load', function() {
  // Start video play-out of the captured audio/video MediaStream once the page
  // has loaded.
  var player = document.getElementById('player');
  player.addEventListener('canplay', function() {
    this.volume = 0.75;
    this.muted = false;
    this.play();
  });
  player.setAttribute('controls', '1');
  player.srcObject = window.currentStream;

  // Add onended event listeners. This detects when tab capture was shut down by
  // closing the tab being captured.
  var tracks = window.currentStream.getTracks();
  for (var i = 0; i < tracks.length; ++i) {
    tracks[i].addEventListener('ended', function() {
      console.log('MediaStreamTrack[' + i + '] ended, shutting down...');
      shutdownReceiver();
    });
  }
});

// Shutdown when the receiver page is closed.
window.addEventListener('beforeunload', shutdownReceiver);