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

ui/gl/scoped_cgl.h

 // Copyright 2014 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 UI_GL_SCOPED_CGL_H_
 #define UI_GL_SCOPED_CGL_H_
 
 #include <OpenGL/OpenGL.h>
 
 #include "base/mac/scoped_typeref.h"
 #include "base/macros.h"
 #include "ui/gl/gl_export.h"
 
 namespace base {
 
 template<>
 struct ScopedTypeRefTraits<CGLContextObj> {
   static CGLContextObj InvalidValue() { return nullptr; }
-  static void Retain(CGLContextObj object) {
-    CGLRetainContext(object);
+  static CGLContextObj Retain(CGLContextObj object) {
+    return CGLRetainContext(object);
   }
   static void Release(CGLContextObj object) {
     CGLReleaseContext(object);
   }
 };
 
 template<>
 struct ScopedTypeRefTraits<CGLPixelFormatObj> {
   static CGLPixelFormatObj InvalidValue() { return nullptr; }
-  static void Retain(CGLPixelFormatObj object) {
-    CGLRetainPixelFormat(object);
+  static CGLPixelFormatObj Retain(CGLPixelFormatObj object) {
+    return CGLRetainPixelFormat(object);
   }
   static void Release(CGLPixelFormatObj object) {
     CGLReleasePixelFormat(object);
   }
 };
 
 }  // namespace base
 
 namespace gfx {
 
 class GL_EXPORT ScopedCGLSetCurrentContext {
  public:
   explicit ScopedCGLSetCurrentContext(CGLContextObj context);
   ~ScopedCGLSetCurrentContext();
  private:
   // Note that if a context is destroyed when it is current, then the current
   // context is changed to NULL. Take out a reference on |previous_context_| to
   // preserve this behavior (when this falls out of scope, |previous_context_|
   // will be made current, then released, so NULL will be current if that
   // release destroys the context).
   base::ScopedTypeRef<CGLContextObj> previous_context_;
 
   DISALLOW_COPY_AND_ASSIGN(ScopedCGLSetCurrentContext);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GL_SCOPED_CGL_H_