Convert //ash from scoped_ptr to std::unique_ptr

ash/display/window_tree_host_manager.cc

Index: ash/display/window_tree_host_manager.cc
diff --git a/ash/display/window_tree_host_manager.cc b/ash/display/window_tree_host_manager.cc
index 9336dfcf494b022a5aa16b74bfc9b3228206ce94..ac93888e5ab72bb794a18b7c15a490801608f9ac 100644
--- a/ash/display/window_tree_host_manager.cc
+++ b/ash/display/window_tree_host_manager.cc
@@ -133,7 +133,7 @@ void SetDisplayPropertiesOnHost(AshWindowTreeHost* ash_host,
       host->GetAcceleratedWidget(), info.GetActiveRotation(), scale);
 #endif
 #endif
-  scoped_ptr<RootWindowTransformer> transformer(
+  std::unique_ptr<RootWindowTransformer> transformer(
       CreateRootWindowTransformerForDisplay(host->window(), display));
   ash_host->SetRootWindowTransformer(std::move(transformer));
 
@@ -446,7 +446,7 @@ void WindowTreeHostManager::SetPrimaryDisplayId(int64_t id) {
   // when the primary id is set after new displays are connected.
   // Only update the layout if it is requested to swap primary display.
   if (layout.primary_id != new_primary_display.id()) {
-    scoped_ptr<display::DisplayLayout> swapped_layout(layout.Copy());
+    std::unique_ptr<display::DisplayLayout> swapped_layout(layout.Copy());
     swapped_layout->placement_list[0].Swap();
     swapped_layout->primary_id = new_primary_display.id();
     display::DisplayIdList list = display_manager->GetCurrentDisplayIdList();