Add W3C encrypted-media tests

third_party/WebKit/LayoutTests/imported/wpt/encrypted-media/scripts/onencrypted.js

+function runTest(config) {
+    var expectedInitData = [];
+    expectedInitData.push(stringToUint8Array(atob(config.keys[0].initData)));
+    expectedInitData.push(stringToUint8Array(atob(config.keys[1].initData)));
+
+    // Will get 2 identical events, one for audio, one for video.
+    var expectedEvents = 2;
+    var currentData;
+
+    async_test(function (test) {
+        var video = config.video,
+            mediaSource,
+            onEncrypted = function (event) {
+                currentData = new Uint8Array(event.initData);
+                assert_equals(event.target, config.video);
+                assert_true(event instanceof window.MediaEncryptedEvent);
+                assert_equals(event.type, 'encrypted');
+                assert_equals(event.initDataType, 'cenc');
+                // At this point we do not know if the event is related to audio or video. So check for both expected init data
+                assert_true(checkInitData(currentData, expectedInitData[0]) || checkInitData(currentData, expectedInitData[1]));
+
+                if (--expectedEvents === 0) {
+                    test.done();
+                }
+            };
+
+        waitForEventAndRunStep('encrypted', video, onEncrypted, test);
+        return testmediasource(config).then(function (source) {
+            mediaSource = source;
+            config.video.src = URL.createObjectURL(mediaSource);
+            return source.done;
+        }).then(function(){
+            video.play();
+        });
+    }, 'encrypted fired on encrypted media file.');
+}
+
+function checkInitData(data, expectedData) {
+    if (data.length !== expectedData.length) {
+        return false;
+    }
+    for (var i = 0; i < data.length; i++) {
+        if (data[i] !== expectedData[i]) {
+            return false;
+        }
+    }
+    return true;
+}