Delete ash-based code for Windows drag-and-drop graphics.

ui/base/dragdrop/os_exchange_data_provider_aura.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_BASE_DRAGDROP_OS_EXCHANGE_DATA_PROVIDER_AURA_H_
 #define UI_BASE_DRAGDROP_OS_EXCHANGE_DATA_PROVIDER_AURA_H_
 
 #include <map>
 
 #include "base/files/file_path.h"
@@ skipping 37 matching lines @@
   bool HasURL(OSExchangeData::FilenameToURLPolicy policy) const override;
   bool HasFile() const override;
   bool HasCustomFormat(const Clipboard::FormatType& format) const
       override;
 
   void SetHtml(const base::string16& html, const GURL& base_url) override;
   bool GetHtml(base::string16* html, GURL* base_url) const override;
   bool HasHtml() const override;
   void SetDragImage(const gfx::ImageSkia& image,
                     const gfx::Vector2d& cursor_offset) override;
-  const gfx::ImageSkia& GetDragImage() const override;
-  const gfx::Vector2d& GetDragImageOffset() const override;
+  gfx::ImageSkia GetDragImage() const override;
+  gfx::Vector2d GetDragImageOffset() const override;
 
  private:
   typedef std::map<Clipboard::FormatType, base::Pickle> PickleData;
 
   // Returns true if |formats_| contains a file format and the file name can be
   // parsed as a URL.
   bool GetFileURL(GURL* url) const;
 
   // Returns true if |formats_| contains a string format and the string can be
   // parsed as a URL.
@@ skipping 23 matching lines @@
   // For HTML format
   base::string16 html_;
   GURL base_url_;
 
   DISALLOW_COPY_AND_ASSIGN(OSExchangeDataProviderAura);
 };
 
 }  // namespace ui
 
 #endif  // UI_BASE_DRAGDROP_OS_EXCHANGE_DATA_PROVIDER_AURA_H_