Convert Aura to use ui::Event.

ui/aura/client/drag_drop_delegate.h

Index: ui/aura/client/drag_drop_delegate.h
===================================================================
--- ui/aura/client/drag_drop_delegate.h	(revision 150582)
+++ ui/aura/client/drag_drop_delegate.h	(working copy)
@@ -7,8 +7,11 @@
 
 #include "ui/aura/aura_export.h"
 
+namespace ui {
+class DropTargetEvent;
+}
+
 namespace aura {
-class DropTargetEvent;
 class Window;
 namespace client {
 
@@ -18,13 +21,13 @@
   // 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.
@@ -32,7 +35,7 @@
 
   // 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() {}