Change AckEvent into request / response

mojo/examples/aura_demo/window_tree_host_mojo.cc

 // Copyright (c) 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 "mojo/examples/aura_demo/window_tree_host_mojo.h"
 
 #include "mojo/examples/aura_demo/demo_context_factory.h"
 #include "mojo/public/bindings/allocation_scope.h"
 #include "mojo/public/c/gles2/gles2.h"
 #include "mojo/services/native_viewport/geometry_conversions.h"
@@ skipping 148 matching lines @@
   bounds_ = gfx::Rect(bounds.position().x(), bounds.position().y(),
                       bounds.size().width(), bounds.size().height());
   window()->SetBounds(gfx::Rect(bounds_.size()));
   OnHostResized(bounds_.size());
 }
 
 void WindowTreeHostMojo::OnDestroyed() {
   base::MessageLoop::current()->Quit();
 }
 
-void WindowTreeHostMojo::OnEvent(const Event& event) {
-  if (!event.location().is_null())
-    native_viewport_->AckEvent(event);
-
+void WindowTreeHostMojo::OnEvent(const Event& event,
+                                 const mojo::Callback<void()>& callback) {
   switch (event.action()) {
     case ui::ET_MOUSE_PRESSED:
     case ui::ET_MOUSE_DRAGGED:
     case ui::ET_MOUSE_RELEASED:
     case ui::ET_MOUSE_MOVED:
     case ui::ET_MOUSE_ENTERED:
     case ui::ET_MOUSE_EXITED: {
       gfx::Point location(event.location().x(), event.location().y());
       ui::MouseEvent ev(static_cast<ui::EventType>(event.action()), location,
                         location, event.flags(), 0);
       SendEventToProcessor(&ev);
       break;
     }
     case ui::ET_KEY_PRESSED:
     case ui::ET_KEY_RELEASED: {
       ui::KeyEvent ev(
           static_cast<ui::EventType>(event.action()),
           static_cast<ui::KeyboardCode>(event.key_data().key_code()),
           event.flags(), event.key_data().is_char());
       SendEventToProcessor(&ev);
       break;
     }
     // TODO(beng): touch, etc.
   }
+  callback.Run();
 };
 
 }  // namespace examples
 }  // namespace mojo