Add W3C encrypted-media tests

third_party/WebKit/LayoutTests/imported/wpt/encrypted-media/scripts/setmediakeys-multiple-times-with-the-same-mediakeys.js

+function runTest(config, qualifier) {
+    var testname = testnamePrefix( qualifier, config.keysystem )
+                         + ', setmediakeys multiple times with the same mediakeys';
+
+    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);
+        }
+
+        navigator.requestMediaKeySystemAccess(config.keysystem, [configuration]).then(function(access) {
+            return access.createMediaKeys();
+        }).then(function(result) {
+            _mediaKeys = result;
+            // Set mediaKeys for first time on video should work.
+            return _video.setMediaKeys(_mediaKeys);
+        }).then(function(result) {
+            assert_equals(_video.mediaKeys, _mediaKeys);
+            // Set mediaKeys on video again should return a resolved promise.
+            return _video.setMediaKeys(_mediaKeys);
+        }).then(function (result) {
+            assert_equals(_video.mediaKeys, _mediaKeys);
+            return testmediasource(config);
+        }).then(function(source) {
+            // Set src attribute on Video Element
+            _video.src = URL.createObjectURL(source);
+            // Set mediaKeys again on video should still return a resolved promise.
+            return _video.setMediaKeys(_mediaKeys);
+        }).then(function() {
+            assert_equals(_video.mediaKeys, _mediaKeys);
+            test.done();
+        }).catch(onFailure);
+    }, testname);
+}