Add W3C encrypted-media tests

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

+function runTest(config, qualifier) {
+    var testname = testnamePrefix( qualifier, config.keysystem )
+                                            + ', setMediaKeys';
+
+    var configuration = getSimpleConfigurationForContent( config.content );
+
+    if ( config.initDataType && config.initData ) {
+        configuration.initDataTypes = [ config.initDataType ];
+    }
+
+    async_test (function (test) {
+        var _video = config.video,
+            _mediaKeys;
+
+        // Test MediaKeys assignment.
+        assert_equals(_video.mediaKeys, null);
+        assert_equals(typeof _video.setMediaKeys, 'function');
+
+        function onFailure(error) {
+            forceTestFailureFromPromise(test, error);
+        }
+
+        // Try setting mediaKeys to null.
+        _video.setMediaKeys(null).then(function(result) {
+            assert_equals(_video.mediaKeys, null);
+
+            // setMediaKeys should fail when setting to the wrong type of object - Date.
+            return _video.setMediaKeys(new Date());
+        }).then(function (result) {
+            assert_unreached('setMediaKeys should fail when setting to wrong kind of object (Date)');
+        }, function(error) {
+            // The error should be TypeError.
+            assert_equals(error.name, 'TypeError', 'setMediaKeys should return a TypeError when setting to wrong kind of object (Date)');
+            return navigator.requestMediaKeySystemAccess(config.keysystem, [configuration]);
+        }).then(function(access) {
+            assert_equals(access.keySystem, config.keysystem)
+            return access.createMediaKeys();
+        }).then(function(result) {
+            _mediaKeys = result;
+            assert_not_equals(_mediaKeys, null);
+            assert_equals(typeof _mediaKeys.createSession, 'function');
+            return _video.setMediaKeys(_mediaKeys);
+        }).then(function(result) {
+            assert_not_equals(_video.mediaKeys, null);
+            assert_equals(_video.mediaKeys, _mediaKeys);
+            test.done();
+        }).catch(onFailure);
+    }, testname);
+}