Convert //ash from scoped_ptr to std::unique_ptr

ash/system/tray/tray_details_view.cc

Index: ash/system/tray/tray_details_view.cc
diff --git a/ash/system/tray/tray_details_view.cc b/ash/system/tray/tray_details_view.cc
index 6e0a5607dabca698e35b0727c45372dd04e86cbd..e7ec1e859b1f2accfafb1c5c8b155068e5de0435 100644
--- a/ash/system/tray/tray_details_view.cc
+++ b/ash/system/tray/tray_details_view.cc
@@ -91,7 +91,7 @@ void TrayDetailsView::CreateScrollableList() {
 
   // Note: |scroller_| takes ownership of |scroll_border_|.
   scroll_border_ = new ScrollBorder;
-  scroller_->SetBorder(scoped_ptr<views::Border>(scroll_border_));
+  scroller_->SetBorder(std::unique_ptr<views::Border>(scroll_border_));
 
   AddChildView(scroller_);
 }