Remove linked_ptr from ash

ash/first_run/desktop_cleaner.cc

Index: ash/first_run/desktop_cleaner.cc
diff --git a/ash/first_run/desktop_cleaner.cc b/ash/first_run/desktop_cleaner.cc
index 8e01b06dc5b027808bfea1f833ff32c7c30190af..443f2a530f85d96ac778a7d7f8781b75c824fc29 100644
--- a/ash/first_run/desktop_cleaner.cc
+++ b/ash/first_run/desktop_cleaner.cc
@@ -95,7 +95,7 @@ DesktopCleaner::DesktopCleaner() {
   for (size_t i = 0; i < arraysize(kContainerIdsToHide); ++i) {
     aura::Window* container =
         Shell::GetContainer(root_window, kContainerIdsToHide[i]);
-    container_hiders_.push_back(make_linked_ptr(new ContainerHider(container)));
+    container_hiders_.push_back(base::MakeUnique<ContainerHider>(container));
   }
   notification_blocker_.reset(new NotificationBlocker());
 }