Get drag and drop working for win aura.

ui/views/widget/drop_target_win.cc

 // Copyright (c) 2011 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 "ui/views/widget/drop_target_win.h"
 
 #include "ui/base/dragdrop/drag_drop_types.h"
 #include "ui/base/dragdrop/os_exchange_data.h"
 #include "ui/base/dragdrop/os_exchange_data_provider_win.h"
 #include "ui/gfx/point.h"
 #include "ui/views/widget/root_view.h"
 #include "ui/views/widget/widget.h"
 
 using ui::OSExchangeData;
 using ui::OSExchangeDataProviderWin;
 
 namespace views {
 
-DropTargetWin::DropTargetWin(internal::RootView* root_view)
-    : ui::DropTarget(root_view->GetWidget()->GetNativeView()),
-      helper_(root_view) {
+DropTargetWin::DropTargetWin(internal::RootView* root_view, HWND drop_target)
+    : ui::DropTarget(drop_target), helper_(root_view) {
 }
 
 DropTargetWin::~DropTargetWin() {
 }
 
 void DropTargetWin::ResetTargetViewIfEquals(View* view) {
   helper_.ResetTargetViewIfEquals(view);
 }
 
 DWORD DropTargetWin::OnDragOver(IDataObject* data_object,
@@ skipping 22 matching lines @@
 
   OSExchangeData data(new OSExchangeDataProviderWin(data_object));
   int drop_operation = ui::DragDropTypes::DropEffectToDragOperation(effect);
   drop_operation = helper_.OnDragOver(data, root_view_location,
                                       drop_operation);
   drop_operation = helper_.OnDrop(data, root_view_location, drop_operation);
   return ui::DragDropTypes::DragOperationToDropEffect(drop_operation);
 }
 
 }  // namespace views