Make media element sources unique to investigate flaky test

LayoutTests/media/activation-behavior.html

Index: LayoutTests/media/activation-behavior.html
diff --git a/LayoutTests/media/activation-behavior.html b/LayoutTests/media/activation-behavior.html
index 0d9a3ccf9ea2233e5bb2f7c98d25be7be519e21b..5c0e93be3d1007fbb75ede583c65ef345cc73f89 100644
--- a/LayoutTests/media/activation-behavior.html
+++ b/LayoutTests/media/activation-behavior.html
@@ -7,11 +7,17 @@
 <script>
 function activation_behavior_test(tagName, src)
 {
+    // FIXME: hack used to investigate http://crbug.com/355489
+    function uniqueSrc()
+    {
+        return src + '?' + Math.random();

[acolwell GONE FROM CHROMIUM, 2014/03/29 00:37:46]

nit: Would a global var make this unique, but more deterministic?

[philipj_slow, 2014/03/29 06:27:15]

Yeah, a simple counter should do the trick, the only thing that matters is that
each media element has a unique source.

+    }
+
     async_test(function(t)
     {
         var e = document.createElement(tagName);
         e.controls = true;
-        e.src = src;
+        e.src = uniqueSrc();
         e.preload = 'auto';
         e.oncanplay = t.step_func(function()
         {
@@ -30,7 +36,7 @@ function activation_behavior_test(tagName, src)
     {
         var e = document.createElement(tagName);
         e.controls = true;
-        e.src = src;
+        e.src = uniqueSrc();
         e.preload = 'auto';
         e.oncanplay = t.step_func(function()
         {
@@ -51,7 +57,8 @@ function activation_behavior_test(tagName, src)
         var e1 = document.createElement(tagName);
         var e2 = document.createElement(tagName);
         e1.controls = true;
-        e1.src = e2.src = src;
+        e1.src = uniqueSrc();
+        e2.src = uniqueSrc();
         e1.preload = e2.preload = 'auto';
         var canplaycount = 0;
         e1.oncanplay = e2.oncanplay = t.step_func(function()
@@ -92,7 +99,7 @@ function activation_behavior_test(tagName, src)
     {
         var e = document.createElement(tagName);
         e.controls = true;
-        e.src = src;
+        e.src = uniqueSrc();
         e.preload = 'auto';
         e.oncanplay = t.step_func(function()
         {
@@ -125,7 +132,7 @@ function activation_behavior_test(tagName, src)
     {
         var e = document.createElement(tagName);
         e.controls = true;
-        e.src = src;
+        e.src = uniqueSrc();
         e.preload = 'auto';
         e.oncanplay = t.step_func(function()
         {
@@ -146,7 +153,7 @@ function activation_behavior_test(tagName, src)
         var e1 = document.createElement(tagName);
         var e2 = document.createElement(tagName);
         e1.controls = true;
-        e1.src = src;
+        e1.src = uniqueSrc();
         e1.preload = 'auto';
         e1.oncanplay = t.step_func(function()
         {