Mojo C++ bindings: support sync methods - part 2

mojo/public/interfaces/bindings/tests/test_sync_methods.mojom

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 module mojo.test;
 
-interface TestSync {
+interface TestCodeGeneration {
   [Sync]
-  Get() => (int32 result);
+  NoInput() => (int32 result);
 
   [Sync]
-  Set(int32 value) => ();
+  NoOutput(int32 value) => ();
 
   [Sync]
+  NoInOut() => ();
+
+  [Sync]
+  HaveInOut(int32 value1, int32 value2) => (int32 result1, int32 result2);
+};
+
+interface TestSync {
+  [Sync]
   Ping() => ();
 
   [Sync]
   Echo(int32 value) => (int32 result);
+
+  AsyncEcho(int32 value) => (int32 result);
 };