Sync Mac scopers with upstream Chromium

base/mac/scoped_typeref.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 MINI_CHROMIUM_BASE_MAC_SCOPED_TYPEREF_H_
+#define MINI_CHROMIUM_BASE_MAC_SCOPED_TYPEREF_H_
+
+#include "base/compiler_specific.h"
+#include "base/logging.h"
+#include "base/memory/scoped_policy.h"
+
+namespace base {
+
+template <typename T>
+struct ScopedTypeRefTraits;
+
+template <typename T, typename Traits = ScopedTypeRefTraits<T>>
+class ScopedTypeRef {
+ public:
+  typedef T element_type;
+
+  ScopedTypeRef(
+      T object = Traits::InvalidValue(),
+      base::scoped_policy::OwnershipPolicy policy = base::scoped_policy::ASSUME)
+      : object_(object) {
+    if (object_ && policy == base::scoped_policy::RETAIN)
+      object_ = Traits::Retain(object_);
+  }
+
+  ScopedTypeRef(const ScopedTypeRef<T, Traits>& that) : object_(that.object_) {
+    if (object_)
+      object_ = Traits::Retain(object_);
+  }
+
+  ~ScopedTypeRef() {
+    if (object_)
+      Traits::Release(object_);
+  }
+
+  ScopedTypeRef& operator=(const ScopedTypeRef<T, Traits>& that) {
+    reset(that.get(), base::scoped_policy::RETAIN);
+    return *this;
+  }
+
+  T* InitializeInto() WARN_UNUSED_RESULT {
+    DCHECK(!object_);
+    return &object_;
+  }
+
+  void reset(T object = Traits::InvalidValue(),
+             base::scoped_policy::OwnershipPolicy policy =
+                 base::scoped_policy::ASSUME) {
+    if (object && policy == base::scoped_policy::RETAIN)
+      object = Traits::Retain(object);
+    if (object_)
+      Traits::Release(object_);
+    object_ = object;
+  }
+
+  bool operator==(T that) const { return object_ == that; }
+
+  bool operator!=(T that) const { return object_ != that; }
+
+  operator T() const { return object_; }
+
+  T get() const { return object_; }
+
+  void swap(ScopedTypeRef& that) {
+    T temp = that.object_;
+    that.object_ = object_;
+    object_ = temp;
+  }
+
+  T release() WARN_UNUSED_RESULT {
+    T temp = object_;
+    object_ = Traits::InvalidValue();
+    return temp;
+  }
+
+ private:
+  T object_;
+};
+
+}  // namespace base
+
+#endif  // MINI_CHROMIUM_BASE_MAC_SCOPED_TYPEREF_H_