Add simple test for VideoTrack.stop().

content/test/data/media/webrtc_test_utilities.js

Index: content/test/data/media/webrtc_test_utilities.js
diff --git a/content/test/data/media/webrtc_test_utilities.js b/content/test/data/media/webrtc_test_utilities.js
index ba894cd56bf09cf0f4ff920fe7eaf0ac5fda5097..26eedaf5f578cf802a2431bb8c5b96b71b56473a 100644
--- a/content/test/data/media/webrtc_test_utilities.js
+++ b/content/test/data/media/webrtc_test_utilities.js
@@ -29,24 +29,51 @@ function detectVideoIn(videoElementName, callback) {
   var height = VIDEO_TAG_HEIGHT;
   var videoElement = $(videoElementName);
   var canvas = $(videoElementName + '-canvas');
+  var old_pixels = [];
   var waitVideo = setInterval(function() {
     var context = canvas.getContext('2d');
     context.drawImage(videoElement, 0, 0, width, height);
-    var pixels = context.getImageData(0, 0, width, height).data;
-
-    if (isVideoPlaying(pixels, width, height)) {
+    var pixels = context.getImageData(0, 0, width, height / 3).data;
+    if (old_pixels.length == pixels.length &&

[phoglund_chromium, 2013/11/14 09:01:18]

Why is this length check necessary?

[perkj_chrome, 2013/11/14 13:29:07]

Its a prerequisite for isVideoPlaying that they are the same lenght.
First time old_pixel.length()= 0;

[phoglund_chromium, 2013/11/14 13:41:05]

Ok. Perhaps we should bake that into isVideoPlaying. Just add a check in that
function that if pixels.length != old_pixels.length, return false. I think that
makes sense for the function since it cannot tell that video is playing given
those circumstances. Moving that check into isVideoPlaying simplifies this
fairly complicated algorithm.

+        isVideoPlaying(pixels, old_pixels)) {
       clearInterval(waitVideo);
       callback();
     }
+    old_pixels = pixels;
   }, 100);
 }
 
+function detectVideoStopped(videoElementName, callback) {

[phoglund_chromium, 2013/11/14 09:01:18]

You should be able to re-use the old function without adding too much
complexity. Imagine you extract a helper function which looks like the two
detection functions but which takes an additional function 'predicate' as an
argument. The predicate should accept two args old_pixels and new_pixels and
return a boolean. Then you can pass in isVideoPlaying in the first one and the
inverse in the second one.

[perkj_chrome, 2013/11/14 13:29:07]

Done.

+  var width = VIDEO_TAG_WIDTH;
+  var height = VIDEO_TAG_HEIGHT;
+  var videoElement = $(videoElementName);
+  var canvas = $(videoElementName + '-canvas');
+  var old_pixels = [];
+  var waitVideo = setInterval(function() {
+    var context = canvas.getContext('2d');
+    context.drawImage(videoElement, 0, 0, width, height);
+    var pixels = context.getImageData(0, 0 , width, height / 3).data;
+    if (old_pixels.length == pixels.length &&
+        !isVideoPlaying(pixels, old_pixels)) {
+      clearInterval(waitVideo);
+      callback();
+    }
+    old_pixels = pixels;
+  }, 300);

[phoglund_chromium, 2013/11/14 09:01:18]

Don't see why this should be different from the other detector.

[perkj_chrome, 2013/11/14 13:29:07]

We can increase it a bit. But it it is lower that the frame rate of the fake
video capture device we will detect false video track stop.

+}
+
 function waitForVideo(videoElement) {
   document.title = 'Waiting for video...';
   addExpectedEvent();
   detectVideoIn(videoElement, function () { eventOccured(); });
 }
 
+function waitForVideoToStop(videoElement) {
+  document.title = 'Waiting for video to stop...';
+  addExpectedEvent();
+  detectVideoStopped(videoElement, function () { eventOccured(); });
+}
+
 function waitForConnectionToStabilize(peerConnection) {
   addExpectedEvent();
   var waitForStabilization = setInterval(function() {
@@ -68,14 +95,11 @@ function eventOccured() {
   }
 }
 
-// This very basic video verification algorithm will be satisfied if any
-// pixels are nonzero in a small sample area in the middle. It relies on the
-// assumption that a video element with null source just presents zeroes.
-function isVideoPlaying(pixels, width, height) {
-  // Sample somewhere near the middle of the image.
-  var middle = width * height / 2;
-  for (var i = 0; i < 20; i++) {
-    if (pixels[middle + i] > 0) {
+//This very basic video verification algorithm will be satisfied if any

[phoglund_chromium, 2013/11/14 09:01:18]

Nit: space between // and letters

[perkj_chrome, 2013/11/14 13:29:07]

Done.

+//pixels are changed.
+function isVideoPlaying(pixels, previouse_pixels) {

[phoglund_chromium, 2013/11/14 09:01:18]

Nit: previous_pixels

[perkj_chrome, 2013/11/14 13:29:07]

Done.

+  for (var i = 0; i < pixels.length; i++) {
+    if (pixels[i] != previouse_pixels[i]) {
       return true;
     }
   }