Improve reliability of EME tests

LayoutTests/media/encrypted-media/encrypted-media-lifetime-reload.html

Index: LayoutTests/media/encrypted-media/encrypted-media-lifetime-reload.html
diff --git a/LayoutTests/media/encrypted-media/encrypted-media-lifetime-reload.html b/LayoutTests/media/encrypted-media/encrypted-media-lifetime-reload.html
index 1e8ac051f29bff8c7fa26aada89ab331fc87000e..cfaafb8b282e3614b96fc1b6eaccc26d152ff68b 100644
--- a/LayoutTests/media/encrypted-media/encrypted-media-lifetime-reload.html
+++ b/LayoutTests/media/encrypted-media/encrypted-media-lifetime-reload.html
@@ -15,8 +15,8 @@
             {
                 var video = document.getElementById('testVideo');
                 var mediaKeySession = null;
-                var isSessionCreated = false;
                 var sessionReadyReceived = false;
+                var encryptedEventCount = 0;
 
                 var rawKey = new Uint8Array([0xeb, 0xdd, 0x62, 0xf1, 0x68, 0x14, 0xd2, 0x7b,
                                              0x68, 0xef, 0x12, 0x2a, 0xfc, 0xe4, 0xae, 0x3c]);
@@ -28,10 +28,12 @@
                     assert_equals(event.type, 'encrypted');
 
                     // The same decryption key is shared by all streams so only
-                    // create a shared session once.
-                    if (isSessionCreated)
+                    // create a shared session once. To avoid timing issues with

[ddorwin, 2014/10/15 23:36:20]

Any idea what "shared" means?

[jrummell, 2014/10/16 00:43:45]

Changed.

+                    // the "message" event being received before the second

[ddorwin, 2014/10/15 23:36:20]

We should be specific about this being related to the expected logs. There's no
functional timing issue.

[jrummell, 2014/10/16 00:43:45]

Done.

+                    // "encrypted" event, only create the session on the second
+                    // event.

[ddorwin, 2014/10/15 23:36:20]

...This also ensures we see both events.

Maybe we should add a check to ensure we don't get a third.

[jrummell, 2014/10/16 00:43:45]

Comment added. expected.txt file ensures it fails if we get a third (or only
one).

+                    if (++encryptedEventCount != 2)
                         return;
-                    isSessionCreated = true;
 
                     mediaKeySession = video.mediaKeys.createSession();
                     waitForEventAndRunStep('message', mediaKeySession, onMessage, test);