Fix ownership bug with ViewObserver::OnViewInputEvent

mojo/examples/nesting_app/nesting_app.cc

 // Copyright 2014 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 "base/basictypes.h"
 #include "base/bind.h"
 #include "mojo/examples/window_manager/window_manager.mojom.h"
 #include "mojo/public/cpp/application/application.h"
 #include "mojo/services/public/cpp/view_manager/view.h"
 #include "mojo/services/public/cpp/view_manager/view_manager.h"
@@ skipping 40 matching lines @@
     root->AddChild(nested);
     nested->SetBounds(gfx::Rect(20, 20, 50, 50));
     nested->Embed("mojo:mojo_embedded_app");
   }
   virtual void OnRootRemoved(ViewManager* view_manager,
                              ViewTreeNode* root) OVERRIDE {
     // TODO(beng): reap views & child nodes.
   }
 
   // Overridden from ViewObserver:
-  virtual void OnViewInputEvent(View* view, EventPtr event) OVERRIDE {
+  virtual void OnViewInputEvent(View* view, const EventPtr& event) OVERRIDE {
     if (event->action == ui::ET_MOUSE_RELEASED)
       window_manager_->CloseWindow(view->node()->id());
   }
 
   IWindowManagerPtr window_manager_;
 
   DISALLOW_COPY_AND_ASSIGN(NestingApp);
 };
 
 }  // namespace examples
 
 // static
 Application* Application::Create() {
   return new examples::NestingApp;
 }
 
-}  // namespace mojo
+}  // namespace mojo