Convert //ash from scoped_ptr to std::unique_ptr

ash/desktop_background/desktop_background_widget_controller.h

Index: ash/desktop_background/desktop_background_widget_controller.h
diff --git a/ash/desktop_background/desktop_background_widget_controller.h b/ash/desktop_background/desktop_background_widget_controller.h
index 680645513d3f30f3de3c55317f6fa3dbadd99c34..11ff17da29b3af7535721150cc603135e7e86e36 100644
--- a/ash/desktop_background/desktop_background_widget_controller.h
+++ b/ash/desktop_background/desktop_background_widget_controller.h
@@ -5,9 +5,10 @@
 #ifndef ASH_DESKTOP_BACKGROUND_DESKTOP_BACKGROUND_WIDGET_CONTROLLER_H_
 #define ASH_DESKTOP_BACKGROUND_DESKTOP_BACKGROUND_WIDGET_CONTROLLER_H_
 
+#include <memory>
+
 #include "ash/ash_export.h"
 #include "base/macros.h"
-#include "base/memory/scoped_ptr.h"
 #include "ui/aura/window.h"
 #include "ui/compositor/layer.h"
 #include "ui/views/widget/widget.h"
@@ -84,7 +85,7 @@ class ASH_EXPORT AnimatingDesktopController {
   DesktopBackgroundWidgetController* GetController(bool pass_ownership);
 
  private:
-  scoped_ptr<DesktopBackgroundWidgetController> controller_;
+  std::unique_ptr<DesktopBackgroundWidgetController> controller_;
 
   DISALLOW_COPY_AND_ASSIGN(AnimatingDesktopController);
 };