Convert //ash from scoped_ptr to std::unique_ptr

ash/system/toast/toast_overlay.h

Index: ash/system/toast/toast_overlay.h
diff --git a/ash/system/toast/toast_overlay.h b/ash/system/toast/toast_overlay.h
index 4bb3c5522c7540ef05917435db8d36dc5016f181..1cd4fa9c5cc9b45b46dcfb522a4db2cd39c95263 100644
--- a/ash/system/toast/toast_overlay.h
+++ b/ash/system/toast/toast_overlay.h
@@ -5,8 +5,9 @@
 #ifndef ASH_SYSTEM_TOAST_TOAST_OVERLAY_H_
 #define ASH_SYSTEM_TOAST_TOAST_OVERLAY_H_
 
+#include <memory>
+
 #include "ash/ash_export.h"
-#include "base/memory/scoped_ptr.h"
 #include "ui/compositor/layer_animation_observer.h"
 #include "ui/events/event.h"
 #include "ui/events/event_constants.h"
@@ -58,8 +59,8 @@ class ASH_EXPORT ToastOverlay : public ui::LayerAnimationObserver {
   bool is_visible_ = false;
   Delegate* const delegate_;
   const std::string text_;
-  scoped_ptr<views::Widget> overlay_widget_;
-  scoped_ptr<ToastOverlayView> overlay_view_;
+  std::unique_ptr<views::Widget> overlay_widget_;
+  std::unique_ptr<ToastOverlayView> overlay_view_;
   gfx::Size widget_size_;
 
   DISALLOW_COPY_AND_ASSIGN(ToastOverlay);