Rewrite most of the scopers in //base/mac to use ScopedTypeRef or ScopedGeneric.

ui/accelerated_widget_mac/display_link_mac.cc

Index: ui/accelerated_widget_mac/display_link_mac.cc
diff --git a/ui/accelerated_widget_mac/display_link_mac.cc b/ui/accelerated_widget_mac/display_link_mac.cc
index 1f0268a675f72105e6a8ed69a44925a7a8dedd34..d9cc46876f9f53a8aea2e04a668421efe6f5ffd5 100644
--- a/ui/accelerated_widget_mac/display_link_mac.cc
+++ b/ui/accelerated_widget_mac/display_link_mac.cc
@@ -15,8 +15,8 @@ namespace base {
 template<>
 struct ScopedTypeRefTraits<CVDisplayLinkRef> {
   static CVDisplayLinkRef InvalidValue() { return nullptr; }
-  static void Retain(CVDisplayLinkRef object) {
-    CVDisplayLinkRetain(object);
+  static CVDisplayLinkRef Retain(CVDisplayLinkRef object) {
+    return CVDisplayLinkRetain(object);
   }
   static void Release(CVDisplayLinkRef object) {
     CVDisplayLinkRelease(object);