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

base/mac/scoped_typeref.h

Index: base/mac/scoped_typeref.h
diff --git a/base/mac/scoped_typeref.h b/base/mac/scoped_typeref.h
index 8cf3e4b75a0785ff381ba4f281b1685612ee28e6..42114141e12164a539a5b4890f8c263af1795e56 100644
--- a/base/mac/scoped_typeref.h
+++ b/base/mac/scoped_typeref.h
@@ -22,7 +22,10 @@ namespace base {
 //   template<>
 //   struct ScopedTypeRefTraits<CGLContextObj> {
 //     static CGLContextObj InvalidValue() { return nullptr; }
-//     static void Retain(CGLContextObj object) { CGLContextRetain(object); }
+//     static CGLContextObj Retain(CGLContextObj object) {

[Mark Mentovai, 2016/01/04 16:09:23]

I think it’s easier to have these return void and consolidate the object_ =
object setting all in this one file, rather than making all of the traits have
to use an extra line. In practice, the extra line in the traits turns into three
extra lines as it did in this example.

Simpler traits are better than more-elegant internals, and I don’t think
you have any traits where the retain function returns something other than its
parameter anyway.

[Robert Sesek, 2016/01/04 16:11:52]

I had to make this change for ScopedBlock, since there's only Block_copy (which
creates a new heap block, potentially from a stack block) not a Block_retain.

+//       CGLContextRetain(object);
+//       return object;
+//     }
 //     static void Release(CGLContextObj object) { CGLContextRelease(object); }
 //   };
 //
@@ -55,13 +58,13 @@ class ScopedTypeRef {
       base::scoped_policy::OwnershipPolicy policy = base::scoped_policy::ASSUME)
       : object_(object) {
     if (object_ && policy == base::scoped_policy::RETAIN)
-      Traits::Retain(object_);
+      object_ = Traits::Retain(object_);
   }
 
   ScopedTypeRef(const ScopedTypeRef<T, Traits>& that)
       : object_(that.object_) {
     if (object_)
-      Traits::Retain(object_);
+      object_ = Traits::Retain(object_);
   }
 
   ~ScopedTypeRef() {
@@ -86,7 +89,7 @@ class ScopedTypeRef {
              base::scoped_policy::OwnershipPolicy policy =
                 base::scoped_policy::ASSUME) {
     if (object && policy == base::scoped_policy::RETAIN)
-      Traits::Retain(object);
+      object = Traits::Retain(object);
     if (object_)
       Traits::Release(object_);
     object_ = object;