Desktop Capture API: Pass Audio Selection Information To Javascript

chrome/common/extensions/docs/examples/api/desktopCapture/app.js

 // Copyright 2013 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.
 
 'use strict';
 
 const DESKTOP_MEDIA = ['screen', 'window', 'tab', 'audio'];
 
 var pending_request_id = null;
 var pc1 = null;
@@ skipping 11 matching lines @@
   }
 });
 
 document.querySelector('#startFromBackgroundPage')
     .addEventListener('click', function(event) {
       chrome.runtime.sendMessage(
           {}, function(response) { console.log(response.farewell); });
     });
 
 // Launch webkitGetUserMedia() based on selected media id.
-function onAccessApproved(id) {
+function onAccessApproved(id, options) {
   if (!id) {
     console.log('Access rejected.');
     return;
   }
 
-  navigator.webkitGetUserMedia({
-    audio:{
+  var audioConstraint = {
       mandatory: {
         chromeMediaSource: 'desktop',
-        chromeMediaSourceId: id} },
+        chromeMediaSourceId: id
+      }
+  };
+
+  console.log(options.canRequestAudioTrack);
+  if (!options.canRequestAudioTrack)
+    audioConstraint = false;
+
+  navigator.webkitGetUserMedia({
+    audio: audioConstraint,
     video: {
       mandatory: {
         chromeMediaSource: 'desktop',
         chromeMediaSourceId: id,
         maxWidth:screen.width,
         maxHeight:screen.height} }
   }, gotStream, getUserMediaError);
 }
 
 function getUserMediaError(error) {
@@ skipping 59 matching lines @@
     var remotePC = (pc === pc1) ? pc2 : pc1;
     remotePC.addIceCandidate(new RTCIceCandidate(event.candidate));
   }
 }
 
 function onIceStateChange(pc, event) {
   if (pc) {
     console.log('ICE state change event: ', event);
   }
 }