Convert Aura to use ui::Event.

ui/aura/client/drag_drop_delegate.h

 // 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.
 
 #ifndef UI_AURA_CLIENT_DRAG_DROP_DELEGATE_H_
 #define UI_AURA_CLIENT_DRAG_DROP_DELEGATE_H_
 
 #include "ui/aura/aura_export.h"
 
+namespace ui {
+class DropTargetEvent;
+}
+
 namespace aura {
-class DropTargetEvent;
 class Window;
 namespace client {
 
 // Delegate interface for drag and drop actions on aura::Window.
 class AURA_EXPORT DragDropDelegate {
  public:
   // OnDragEntered is invoked when the mouse enters this window during a drag &
   // drop session. This is immediately followed by an invocation of
   // OnDragUpdated, and eventually one of OnDragExited or OnPerformDrop.
-  virtual void OnDragEntered(const DropTargetEvent& event) = 0;
+  virtual void OnDragEntered(const ui::DropTargetEvent& event) = 0;
 
   // Invoked during a drag and drop session while the mouse is over the window.
   // This should return a bitmask of the DragDropTypes::DragOperation supported
   // based on the location of the event. Return 0 to indicate the drop should
   // not be accepted.
-  virtual int OnDragUpdated(const DropTargetEvent& event) = 0;
+  virtual int OnDragUpdated(const ui::DropTargetEvent& event) = 0;
 
   // Invoked during a drag and drop session when the mouse exits the window, or
   // when the drag session was canceled and the mouse was over the window.
   virtual void OnDragExited() = 0;
 
   // Invoked during a drag and drop session when OnDragUpdated returns a valid
   // operation and the user release the mouse.
-  virtual int OnPerformDrop(const DropTargetEvent& event) = 0;
+  virtual int OnPerformDrop(const ui::DropTargetEvent& event) = 0;
 
  protected:
   virtual ~DragDropDelegate() {}
 };
 
 AURA_EXPORT void SetDragDropDelegate(Window* window,
                                      DragDropDelegate* delegate);
 AURA_EXPORT DragDropDelegate* GetDragDropDelegate(Window* window);
 
 }  // namespace client
 }  // namespace aura
 
 #endif  // UI_AURA_CLIENT_DRAG_DROP_DELEGATE_H_