Move more dnd related files to ui/base

ui/base/dragdrop/drop_target.h

-// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// 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.
 
-#ifndef APP_WIN_DROP_TARGET_H_
-#define APP_WIN_DROP_TARGET_H_
+#ifndef UI_BASE_DRAGDROP_DROP_TARGET_H_
+#define UI_BASE_DRAGDROP_DROP_TARGET_H_
 #pragma once
 
 #include <objidl.h>
 
 #include "base/ref_counted.h"
 
 // Windows interface.
 struct IDropTargetHelper;
 
-namespace app {
-namespace win {
+namespace ui {
 
 // A DropTarget implementation that takes care of the nitty gritty
 // of dnd. While this class is concrete, subclasses will most likely
 // want to override various OnXXX methods.
 //
 // Because DropTarget is ref counted you shouldn't delete it directly,
 // rather wrap it in a scoped_refptr. Be sure and invoke RevokeDragDrop(m_hWnd)
 // before the HWND is deleted too.
 //
 // This class is meant to be used in a STA and is not multithread-safe.
@@ skipping 95 matching lines @@
 
   // Whether or not we are currently processing drag notifications for drags
   // initiated in this window.
   bool suspended_;
 
   LONG ref_count_;
 
   DISALLOW_COPY_AND_ASSIGN(DropTarget);
 };
 
-}  // namespace win
-}  // namespace app
+}  // namespace ui
 
-#endif  // APP_WIN_DROP_TARGET_H_
+#endif  // UI_BASE_DRAGDROP_DROP_TARGET_H_