Ported media stream track enable-disable test to content module.

content/test/data/media/webrtc_test_utilities.js

 // Copyright (c) 2012 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.
 
 // These must match with how the video and canvas tags are declared in html.
 const VIDEO_TAG_WIDTH = 320;
 const VIDEO_TAG_HEIGHT = 240;
 
 // Fake video capture background green is of value 135.
 const COLOR_BACKGROUND_GREEN = 135;
@@ skipping 52 matching lines @@
   addExpectedEvent();
   detectVideoPlaying(videoElement, function () { eventOccured(); });
 }
 
 function waitForVideoToStop(videoElement) {
   document.title = 'Waiting for video to stop...';
   addExpectedEvent();
   detectVideoStopped(videoElement, function () { eventOccured(); });
 }
 
-function waitForConnectionToStabilize(peerConnection) {
-  addExpectedEvent();
+function waitForConnectionToStabilize(peerConnection, callback) {
   var waitForStabilization = setInterval(function() {
     if (peerConnection.signalingState == 'stable') {
       clearInterval(waitForStabilization);
-      eventOccured();
+      callback();
     }
   }, 100);
 }
 
 function addExpectedEvent() {
   ++gNumberOfExpectedEvents;
 }
 
 function eventOccured() {
   ++gNumberOfEvents;
@@ skipping 102 matching lines @@
         detectedAspectRatioString += " cropped";
       } else
         detectedAspectRatioString += " letterbox";
 
       console.log("Original image is: " + detectedAspectRatioString);
       callback(detectedAspectRatioString);
     }
   },
                               50);
 }