Keep the mouse cursor within desktop

ui/aura/dispatcher_win.cc

 // Copyright (c) 2012 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/compiler_specific.h"
 #include "base/message_loop.h"
-#include "ui/aura/env.h"
-#include "ui/aura/root_window.h"
 
 namespace aura {
 
-class DispatcherWin : public Dispatcher {
+class DispatcherWin : public MessageLoop::Dispatcher {
  public:
   DispatcherWin() {}
   virtual ~DispatcherWin() {}
 
   // Overridden from MessageLoop::Dispatcher:
   virtual bool Dispatch(const MSG& msg) OVERRIDE;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(DispatcherWin);
 };
 
 bool DispatcherWin::Dispatch(const MSG& msg) {
   TranslateMessage(&msg);
   DispatchMessage(&msg);
   return true;
 }
 
-Dispatcher* CreateDispatcher() {
+MessageLoop::Dispatcher* CreateDispatcher() {
   return new DispatcherWin;
 }
 
 }  // namespace aura