chrome/common/extensions/docs/examples/api/tabCapture/eventPage.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.

// The window (tab) opened and navigated to receiver.html.
var receiver = null;

// Open a new window of receiver.html when browser action icon is clicked.
chrome.browserAction.onClicked.addListener(function(tab) {
  chrome.tabCapture.capture(
    {video: true, audio: true,
     videoConstraints: {
       mandatory: {
         // If minWidth/Height have the same aspect ratio (e.g., 16:9) as
         // maxWidth/Height, the implementation will letterbox/pillarbox as
         // needed. Otherwise, set minWidth/Height to 0 to allow output video
         // to be of any arbitrary size.
         minWidth: 16,
         minHeight: 9,
         maxWidth: 854,
         maxHeight: 480,
         maxFrameRate: 60,  // Note: Frame rate is variable (0 <= x <= 60).
       },
     },
    },
    function(stream) {
      if (!stream) {
        console.error('Error starting tab capture: ' +
                      (chrome.runtime.lastError.message || 'UNKNOWN'));
        return;
      }
      if (receiver != null) {
        receiver.close();
      }
      receiver = window.open('receiver.html');
      receiver.currentStream = stream;
    }
  );
});