Support dynamic switching between integrated and discrete GPUs on Mac OS X.

base/mac/scoped_cftyperef.h

 // Copyright (c) 2010 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_
 #pragma once
 
 #include <CoreFoundation/CoreFoundation.h>
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 
 namespace base {
 namespace mac {
 
+// This class wraps the CoreFoundation routine CFRelease() in a class
+// that can be passed as a template argument to ScopedCFTypeRef below.
+class ScopedCFTypeRefRelease {
+ public:
+  inline void operator()(CFTypeRef x) const {
+    CFRelease(x);
+  }
+};
+
 // ScopedCFTypeRef<> is patterned after scoped_ptr<>, but maintains ownership
 // of a CoreFoundation object: any object that can be represented as a
 // CFTypeRef.  Style deviations here are solely for compatibility with
 // scoped_ptr<>'s interface, with which everyone is already familiar.
 //
 // When ScopedCFTypeRef<> takes ownership of an object (in the constructor or
 // in reset()), it takes over the caller's existing ownership claim.  The
 // caller must own the object it gives to ScopedCFTypeRef<>, and relinquishes
 // an ownership claim to that object.  ScopedCFTypeRef<> does not call
 // CFRetain().
-template<typename CFT>
+//
+// The second template argument can be used to specify a functor used
+// to free the object. This allows this class to manage the lifetime
+// of objects similar to Core Foundation types, where the pointer-ness
+// is embedded in the type name) but with specialized releasing routines.

[Mark Mentovai, 2011/10/13 20:20:48]

The ) doesn’t close any (.

+template<typename CFT, class FreeProc = ScopedCFTypeRefRelease>
 class ScopedCFTypeRef {
  public:
   typedef CFT element_type;
 
   explicit ScopedCFTypeRef(CFT object = NULL)
       : object_(object) {
   }
 
   ~ScopedCFTypeRef() {
-    if (object_)
-      CFRelease(object_);
+    if (object_) {
+      FreeProc free_proc;
+      free_proc(object_);
+    }
   }
 
   void reset(CFT object = NULL) {
-    if (object_)
-      CFRelease(object_);
+    if (object_) {
+      FreeProc free_proc;
+      free_proc(object_);
+    }
     object_ = object;
   }
 
   bool operator==(CFT that) const {
     return object_ == that;
   }
 
   bool operator!=(CFT that) const {
     return object_ != that;
   }
@@ skipping 24 matching lines @@
  private:
   CFT object_;
 
   DISALLOW_COPY_AND_ASSIGN(ScopedCFTypeRef);
 };
 
 }  // namespace mac
 }  // namespace base
 
 #endif  // BASE_MAC_SCOPED_CFTYPEREF_H_