Replace scoped_ptr with std::unique_ptr in //ui

ui/wm/public/scoped_drag_drop_disabler.h

 // Copyright 2015 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_WM_PUBLIC_SCOPED_DRAG_DROP_DISABLER_H_
 #define UI_WM_PUBLIC_SCOPED_DRAG_DROP_DISABLER_H_
 
+#include <memory>
+
 #include "base/macros.h"
-#include "base/memory/scoped_ptr.h"
 #include "ui/aura/window_observer.h"
 
 namespace aura {
 class Window;
 
 namespace client {
 class DragDropClient;
 
 // ScopedDragDropDisabler is used to temporarily replace the drag'n'drop client
 // for a window with a "no-op" client. Upon construction, it installs a new
 // client on the window, and upon destruction, it restores the previous one.
 class AURA_EXPORT ScopedDragDropDisabler : public WindowObserver {
  public:
   explicit ScopedDragDropDisabler(Window* window);
   ~ScopedDragDropDisabler() override;
 
  private:
   // WindowObserver:
   void OnWindowDestroyed(Window* window) override;
 
   Window* window_;
   DragDropClient* old_client_;
-  scoped_ptr<DragDropClient> new_client_;
+  std::unique_ptr<DragDropClient> new_client_;
 
   DISALLOW_COPY_AND_ASSIGN(ScopedDragDropDisabler);
 };
 
 }  // namespace client
 }  // namespace aura
 
 #endif  // UI_WM_PUBLIC_SCOPED_DRAG_DROP_DISABLER_H_