Implement media::VideoDecodeAccelerator on Mac

base/mac/scoped_cftyperef.h

-// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// 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_
 #pragma once
 
 #include <CoreFoundation/CoreFoundation.h>
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 
 namespace base {
 namespace mac {
 
+enum OwnershipPolicy {
+  ASSUME,
+  RETAIN
+};
+
 // 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().
+// By default, ScopedCFTypeRef<> takes ownership of an object (in the
+// constructor or in reset()) by taking 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(). This behavior is parametrized 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.
+
 template<typename CFT>
 class ScopedCFTypeRef {
  public:
   typedef CFT element_type;
 
-  explicit ScopedCFTypeRef(CFT object = NULL)
+  explicit ScopedCFTypeRef(CFT object = NULL,
+                           OwnershipPolicy policy = ASSUME)
       : object_(object) {
+    if (object_ && policy == RETAIN)
+      CFRetain(object_);
+  }
+
+  ScopedCFTypeRef(const ScopedCFTypeRef<CFT>& that)
+      : object_(that.object_) {
+    if (object_)
+      CFRetain(object_);
   }
 
   ~ScopedCFTypeRef() {
     if (object_)
       CFRelease(object_);
   }
 
-  void reset(CFT object = NULL) {
+  ScopedCFTypeRef& operator=(const ScopedCFTypeRef<CFT>& that) {
+    reset(that.get(), RETAIN);
+    return *this;
+  }
+
+  void reset(CFT object = NULL,
+             OwnershipPolicy policy = ASSUME) {
+    if (object && policy == RETAIN)
+      CFRetain(object);
     if (object_)
       CFRelease(object_);
     object_ = object;
   }
 
   bool operator==(CFT that) const {
     return object_ == that;
   }
 
   bool operator!=(CFT that) const {
@@ skipping 18 matching lines @@
   // a wrapper for CFRelease().  To force a ScopedCFTypeRef<> object to call
   // CFRelease(), use ScopedCFTypeRef<>::reset().
   CFT release() WARN_UNUSED_RESULT {
     CFT temp = object_;
     object_ = NULL;
     return temp;
   }
 
  private:
   CFT object_;
-
-  DISALLOW_COPY_AND_ASSIGN(ScopedCFTypeRef);
 };
 
 }  // namespace mac
 }  // namespace base
 
 #endif  // BASE_MAC_SCOPED_CFTYPEREF_H_