Add EME content test that forces garbage collection

LayoutTests/media/video-test.js

Index: LayoutTests/media/video-test.js
diff --git a/LayoutTests/media/video-test.js b/LayoutTests/media/video-test.js
index e558c1db9a90094ddbfc71a27856c090e750edfb..a0e29d696b620b39832708703927307a7829c97b 100644
--- a/LayoutTests/media/video-test.js
+++ b/LayoutTests/media/video-test.js
@@ -364,3 +364,18 @@ function waitForEventsAndCall(eventList, func)
         eventList[i][0].addEventListener(requiredEvents[i], _eventCallback, true);
     }
 }
+
+function forceGC()
+{
+    // Available in content_tests
+    if (window.GCController)
+        return GCController.collect();
+
+    // Available if '--js-flags="--expose_gc"' specified
+    if (typeof gc == 'function')
+        return gc();
+
+    // Force garbage collection
+    for (var ndx = 0; ndx < 99000; ndx++)
+        var str = new String("1234");
+}