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

base/mac/scoped_cftyperef.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef BASE_MAC_SCOPED_CFTYPEREF_H_
 #define BASE_MAC_SCOPED_CFTYPEREF_H_
 
 #include <CoreFoundation/CoreFoundation.h>
 
 #include "base/mac/scoped_typeref.h"
@@ skipping 12 matching lines @@
 // call CFRetain(). This behavior is parameterized by the |OwnershipPolicy|
 // enum. If the value |RETAIN| is passed (in the constructor or in reset()),
 // then ScopedCFTypeRef<> will call CFRetain() on the object, and the initial
 // ownership is not changed.
 
 namespace internal {
 
 template<typename CFT>
 struct ScopedCFTypeRefTraits {
   static CFT InvalidValue() { return nullptr; }
-  static void Retain(CFT object) {
+  static CFT Retain(CFT object) {
     CFRetain(object);
+    return object;
   }
   static void Release(CFT object) {
     CFRelease(object);
   }
 };
 
 }  // namespace internal
 
 template<typename CFT>
 using ScopedCFTypeRef =
     ScopedTypeRef<CFT, internal::ScopedCFTypeRefTraits<CFT>>;
 
 }  // namespace base
 
 #endif  // BASE_MAC_SCOPED_CFTYPEREF_H_