Convert //ash from scoped_ptr to std::unique_ptr

ash/wm/resize_shadow.h

Index: ash/wm/resize_shadow.h
diff --git a/ash/wm/resize_shadow.h b/ash/wm/resize_shadow.h
index 4ab6d7bcac4c210530862bd8d16ac96b2c836ee0..724c4f73fd7d958778b6f209187ac6e4f065ddd1 100644
--- a/ash/wm/resize_shadow.h
+++ b/ash/wm/resize_shadow.h
@@ -5,8 +5,9 @@
 #ifndef ASH_WM_RESIZE_SHADOW_H_
 #define ASH_WM_RESIZE_SHADOW_H_
 
+#include <memory>
+
 #include "base/macros.h"
-#include "base/memory/scoped_ptr.h"
 
 namespace aura {
 class Window;
@@ -50,7 +51,7 @@ class ResizeShadow {
 
  private:
   // Images for the shadow effect.
-  scoped_ptr< ::wm::ImageGrid> image_grid_;
+  std::unique_ptr<::wm::ImageGrid> image_grid_;
 
   // Hit test value from last call to ShowForHitTest().  Used to prevent
   // repeatedly triggering the same animations for the same hit.