Add W3C encrypted-media tests

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

+function runTest(config,qualifier) {
+
+    var testname = testnamePrefix(qualifier, config.keysystem) + ', expiration';
+
+    var configuration = getSimpleConfigurationForContent(config.content);
+    if (config.initDataType && config.initData) {
+        configuration.initDataTypes = [config.initDataType];
+    }
+
+    async_test(function(test) {
+
+        var _mediaKeys,
+            _mediaKeySession;
+
+        function onFailure(error) {
+            forceTestFailureFromPromise(test, error);
+        }
+
+        function onMessage(event) {
+            assert_equals(event.target, _mediaKeySession);
+            assert_true(event instanceof window.MediaKeyMessageEvent);
+            assert_equals(event.type, 'message');
+
+            assert_in_array(event.messageType, [ 'license-request', 'individualization-request' ] );
+
+            config.messagehandler(event.messageType, event.message, {expiration: config.expiration}).then(function(response) {
+                return event.target.update(response);
+            }).then(test.step_func(function() {
+                assert_approx_equals(event.target.expiration, config.expiration, 4000, "expiration attribute should equal provided expiration time");
+                test.done();
+            })).catch(onFailure);
+        }
+
+        navigator.requestMediaKeySystemAccess(config.keysystem, [configuration]).then(function(access) {
+            return access.createMediaKeys();
+        }).then(function(mediaKeys) {
+            _mediaKeys = mediaKeys;
+            _mediaKeySession = _mediaKeys.createSession( 'temporary' );
+            waitForEventAndRunStep('message', _mediaKeySession, onMessage, test);
+            return _mediaKeySession.generateRequest(config.initDataType, config.initData);
+        }).catch(onFailure);
+    }, testname);
+}