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

ui/aura/mus/os_exchange_data_provider_mus.cc

 // Copyright 2016 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/aura/mus/os_exchange_data_provider_mus.h"
 
 #include <memory>
 #include <string>
 #include <utility>
 #include <vector>
@@ skipping 307 matching lines @@
 #endif
 
 #if defined(USE_AURA) || defined(OS_MACOSX)
 void OSExchangeDataProviderMus::SetDragImage(
     const gfx::ImageSkia& image,
     const gfx::Vector2d& cursor_offset) {
   drag_image_ = image;
   drag_image_offset_ = cursor_offset;
 }
 
-const gfx::ImageSkia& OSExchangeDataProviderMus::GetDragImage() const {
+gfx::ImageSkia OSExchangeDataProviderMus::GetDragImage() const {
   return drag_image_;
 }
 
-const gfx::Vector2d& OSExchangeDataProviderMus::GetDragImageOffset() const {
+gfx::Vector2d OSExchangeDataProviderMus::GetDragImageOffset() const {
   return drag_image_offset_;
 }
 #endif
 
 bool OSExchangeDataProviderMus::GetFileURL(GURL* url) const {
   base::FilePath file_path;
   if (!GetFilename(&file_path))
     return false;
 
   GURL test_url = net::FilePathToFileURL(file_path);
@@ skipping 13 matching lines @@
   GURL test_url(str);
   if (!test_url.is_valid())
     return false;
 
   if (url)
     *url = test_url;
   return true;
 }
 
 }  // namespace aura