Fix onKeyAdded check causing flakiness in the tests.

content/test/data/media/encrypted_media_player.html

Index: content/test/data/media/encrypted_media_player.html
diff --git a/content/test/data/media/encrypted_media_player.html b/content/test/data/media/encrypted_media_player.html
index 8c7d0cd24b729f4bfc5bf04c97f00faa88c4f15b..3cf753dab506f72083ec7fdce0b7c56540001c15 100644
--- a/content/test/data/media/encrypted_media_player.html
+++ b/content/test/data/media/encrypted_media_player.html
@@ -10,11 +10,12 @@
       var video = document.querySelector('video');
 
       function onTimeUpdate() {
-        // webkitkeyadded should have been fired before playback.
-        if (!video.receivedKeyAdded)
-          failTest('Key added event not received.');
         if (video.currentTime < 1)
           return;
+        // webkitkeyadded happens right before playback, we check for it after

[ddorwin, 2013/01/03 23:29:55]

I suggest something like:
// keyadded may be fired around the start of playback; check for it after a
delay to avoid timing issues.

[shadi, 2013/01/04 00:09:19]

Done.

+        // time update to avoid timing issues.
+        if (!video.receivedKeyAdded)
+          failTest('Key added event not received.');
         if (video.isHeartbeatExpected && !video.receivedHeartbeat)
           failTest('Heartbeat keymessage event not received.');
         video.removeEventListener('ended', failTest);