[iOS/OS X] Allow base::scoped_nsobject<> to be used when ARC is enabled.

base/mac/scoped_block.h

Index: base/mac/scoped_block.h
diff --git a/base/mac/scoped_block.h b/base/mac/scoped_block.h
index bc2688f13ac064d9c1acfd37fedc37d72c52b458..d46a4e3101f174eef879bb3e5b89f81fd7e0c387 100644
--- a/base/mac/scoped_block.h
+++ b/base/mac/scoped_block.h
@@ -14,11 +14,14 @@ namespace mac {
 
 namespace internal {
 
+id ScopedBlockTraitsRetain(id block);

[Mark Mentovai, 2016/04/05 00:09:15]

Blocks are normally typed as const void*. If you use that, does it break ARC?
That would be worth a comment, because the type mismatch compared to <Block.h>
is obvious.

Does this file need to be #included by any non-Objective C++ files?

+void ScopedBlockTraitsRelease(id block);
+
 template <typename B>
 struct ScopedBlockTraits {
   static B InvalidValue() { return nullptr; }
-  static B Retain(B block) { return Block_copy(block); }
-  static void Release(B block) { Block_release(block); }
+  static B Retain(B block) { return ScopedBlockTraitsRetain(block); }
+  static void Release(B block) { ScopedBlockTraitsRelease(block); }
 };
 
 }  // namespace internal