Convert //ash from scoped_ptr to std::unique_ptr

ash/wm/system_background_controller.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 ASH_WM_SYSTEM_BACKGROUND_CONTROLLER_H_
 #define ASH_WM_SYSTEM_BACKGROUND_CONTROLLER_H_
 
+#include <memory>
 #include <string>
 
 #include "ash/ash_export.h"
 #include "base/macros.h"
-#include "base/memory/scoped_ptr.h"
 #include "third_party/skia/include/core/SkColor.h"
 #include "ui/aura/window_observer.h"
 
 namespace ui {
 class Layer;
 }
 
 namespace ash {
 
 // SystemBackgroundController manages a ui::Layer that's stacked at the bottom
@@ skipping 12 matching lines @@
   // aura::WindowObserver overrides:
   void OnWindowBoundsChanged(aura::Window* root,
                              const gfx::Rect& old_bounds,
                              const gfx::Rect& new_bounds) override;
 
  private:
   class HostContentLayerDelegate;
 
   aura::Window* root_window_;  // not owned
 
-  scoped_ptr<ui::Layer> layer_;
+  std::unique_ptr<ui::Layer> layer_;
 
   DISALLOW_COPY_AND_ASSIGN(SystemBackgroundController);
 };
 
 }  // namespace ash
 
 #endif  // ASH_WM_SYSTEM_BACKGROUND_CONTROLLER_H_