Convert //ash from scoped_ptr to std::unique_ptr

ash/mus/keyboard_ui_mus.h

Index: ash/mus/keyboard_ui_mus.h
diff --git a/ash/mus/keyboard_ui_mus.h b/ash/mus/keyboard_ui_mus.h
index c7bcb241e8cef114da54b04546e2b8988c0fca7e..4a0b552116e86338dabf568f6c747691688de799 100644
--- a/ash/mus/keyboard_ui_mus.h
+++ b/ash/mus/keyboard_ui_mus.h
@@ -5,6 +5,8 @@
 #ifndef ASH_MUS_KEYBOARD_UI_MUS_H_
 #define ASH_MUS_KEYBOARD_UI_MUS_H_
 
+#include <memory>
+
 #include "ash/keyboard/keyboard_ui.h"
 #include "base/macros.h"
 #include "mojo/public/cpp/bindings/binding.h"
@@ -22,7 +24,7 @@ class KeyboardUIMus : public KeyboardUI,
   explicit KeyboardUIMus(mojo::Connector* connector);
   ~KeyboardUIMus() override;
 
-  static scoped_ptr<KeyboardUI> Create(mojo::Connector* connector);
+  static std::unique_ptr<KeyboardUI> Create(mojo::Connector* connector);
 
   // KeyboardUI:
   void Hide() override;