Change AckEvent into request / response

mojo/examples/compositor_app/compositor_app.cc

 // Copyright 2013 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.
 
 #include <stdio.h>
 #include <string>
 
 #include "base/macros.h"
 #include "base/message_loop/message_loop.h"
 #include "mojo/examples/compositor_app/compositor_host.h"
@@ skipping 44 matching lines @@
   }
 
   virtual void OnDestroyed() OVERRIDE {
     base::MessageLoop::current()->Quit();
   }
 
   virtual void OnBoundsChanged(const Rect& bounds) OVERRIDE {
     host_->SetSize(bounds.size());
   }
 
-  virtual void OnEvent(const Event& event) OVERRIDE {
-    if (!event.location().is_null()) {
-      viewport_->AckEvent(event);
-    }
+  virtual void OnEvent(const Event& event,
+                       const mojo::Callback<void()>& callback) OVERRIDE {
+    callback.Run();
   }
 
  private:
   RemotePtr<NativeViewport> viewport_;
   scoped_ptr<CompositorHost> host_;
 };
 
 }  // namespace examples
 }  // namespace mojo
 
 extern "C" SAMPLE_APP_EXPORT MojoResult CDECL MojoMain(
     MojoHandle shell_handle) {
   base::MessageLoop loop;
   mojo::GLES2Initializer gles2;
 
   mojo::examples::SampleApp app(shell_handle);
   loop.Run();
   return MOJO_RESULT_OK;
 }