Add W3C encrypted-media tests

third_party/WebKit/LayoutTests/imported/wpt/encrypted-media/scripts/check-initdata-type.js

+ function runTest( config, qualifier )
+ {
+    function checkInitDataType(initDataType)
+    {
+        return isInitDataTypeSupported(initDataType).then(function(result) {
+            // If |initDataType| is not supported, simply succeed.
+            if (!result)
+                return Promise.resolve('Not supported');
+
+            return navigator.requestMediaKeySystemAccess( config.keysystem, getSimpleConfigurationForInitDataType(initDataType))
+                .then(function(access) {
+                    return access.createMediaKeys();
+                }).then(function(mediaKeys) {
+                    var mediaKeySession = mediaKeys.createSession();
+                    var initData = getInitData(initDataType);
+                    return mediaKeySession.generateRequest(initDataType, initData);
+                });
+        });
+    }
+
+    promise_test(function()
+    {
+        return checkInitDataType('webm');
+    }, testnamePrefix( qualifier, config.keysystem )  + ' support for "webm".');
+
+    promise_test(function()
+    {
+        return checkInitDataType('cenc');
+    }, testnamePrefix( qualifier, config.keysystem ) + ' support for "cenc".');
+
+    promise_test(function()
+    {
+        return checkInitDataType('keyids');
+    }, testnamePrefix( qualifier, config.keysystem ) + ' support for "keyids".');
+}