Convert //ash from scoped_ptr to std::unique_ptr

ash/system/tray/default_system_tray_delegate.h

Index: ash/system/tray/default_system_tray_delegate.h
diff --git a/ash/system/tray/default_system_tray_delegate.h b/ash/system/tray/default_system_tray_delegate.h
index 7503c28e99a807a08168a619592293d4b43196f3..fe3ee8e29147c1b6a1461f3eb5e3c277e75a35e5 100644
--- a/ash/system/tray/default_system_tray_delegate.h
+++ b/ash/system/tray/default_system_tray_delegate.h
@@ -5,11 +5,12 @@
 #ifndef ASH_SYSTEM_TRAY_DEFAULT_SYSTEM_TRAY_DELEGATE_H_
 #define ASH_SYSTEM_TRAY_DEFAULT_SYSTEM_TRAY_DELEGATE_H_
 
+#include <memory>
+
 #include "ash/ash_export.h"
 #include "ash/system/tray/system_tray_delegate.h"
 #include "base/compiler_specific.h"
 #include "base/macros.h"
-#include "base/memory/scoped_ptr.h"
 
 namespace ash {
 
@@ -33,12 +34,12 @@ class ASH_EXPORT DefaultSystemTrayDelegate : public SystemTrayDelegate {
   bool GetBluetoothDiscovering() override;
   VolumeControlDelegate* GetVolumeControlDelegate() const override;
   void SetVolumeControlDelegate(
-      scoped_ptr<VolumeControlDelegate> delegate) override;
+      std::unique_ptr<VolumeControlDelegate> delegate) override;
   int GetSystemTrayMenuWidth() override;
 
  private:
   bool bluetooth_enabled_;
-  scoped_ptr<VolumeControlDelegate> volume_control_delegate_;
+  std::unique_ptr<VolumeControlDelegate> volume_control_delegate_;
 
   DISALLOW_COPY_AND_ASSIGN(DefaultSystemTrayDelegate);
 };