Remove ScopedVector from tools/gn/.

tools/gn/loader.cc

Index: tools/gn/loader.cc
diff --git a/tools/gn/loader.cc b/tools/gn/loader.cc
index 417a8914d17e01b492d51b28847356ffcd59dea5..a07ee5ab2621884a503c6fe874aa105721a89390 100644
--- a/tools/gn/loader.cc
+++ b/tools/gn/loader.cc
@@ -278,10 +278,8 @@ void LoaderImpl::BackgroundLoadFile(const Settings* settings,
 
 
   // Pass all of the items that were defined off to the builder.
-  for (auto*& item : collected_items) {
-    settings->build_settings()->ItemDefined(base::WrapUnique(item));
-    item = nullptr;
-  }
+  for (auto& item : collected_items)
+    settings->build_settings()->ItemDefined(std::move(item));
 
   trace.Done();