Convert //ash from scoped_ptr to std::unique_ptr

ash/frame/caption_buttons/frame_size_button.h

Index: ash/frame/caption_buttons/frame_size_button.h
diff --git a/ash/frame/caption_buttons/frame_size_button.h b/ash/frame/caption_buttons/frame_size_button.h
index 84cf84839c22a39cb0562253fb5d5bccddcf58eb..b96ad5c4e87fec4ef99669e960b0096323ac13dd 100644
--- a/ash/frame/caption_buttons/frame_size_button.h
+++ b/ash/frame/caption_buttons/frame_size_button.h
@@ -5,6 +5,8 @@
 #ifndef ASH_FRAME_CAPTION_BUTTONS_FRAME_SIZE_BUTTON_H_
 #define ASH_FRAME_CAPTION_BUTTONS_FRAME_SIZE_BUTTON_H_
 
+#include <memory>
+
 #include "ash/ash_export.h"
 #include "ash/frame/caption_buttons/frame_caption_button.h"
 #include "ash/frame/caption_buttons/frame_size_button_delegate.h"
@@ -112,7 +114,7 @@ class ASH_EXPORT FrameSizeButton : public FrameCaptionButton {
   // Displays a preview of how the window's bounds will change as a result of
   // snapping the window left or right. The preview is only visible if the snap
   // left or snap right button is pressed.
-  scoped_ptr<PhantomWindowController> phantom_window_controller_;
+  std::unique_ptr<PhantomWindowController> phantom_window_controller_;
 
   DISALLOW_COPY_AND_ASSIGN(FrameSizeButton);
 };