Add EME content test that forces garbage collection

LayoutTests/media/video-test.js

 
 var video = null;
 var mediaElement = document; // If not set, an event from any element will trigger a waitForEvent() callback.
 var console = null;
 var printFullTestDetails = true; // This is optionaly switched of by test whose tested values can differ. (see disableFullTestDetailsPrinting())
 var Failed = false;
 
 var track = null; // Current TextTrack being tested.
 var cues = null; // Current TextTrackCueList being tested.
 var numberOfTrackTests = 0;
@@ skipping 346 matching lines @@
 
         func();
     }
 
     requiredEvents = [];
     for (var i = 0; i < eventList.length; i++) {
         requiredEvents[i] = eventList[i][1];
         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");
+}