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diff --git a/base/memory/ref_counted.h b/base/memory/ref_counted.h
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+// Copyright (c) 2011 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_MEMORY_REF_COUNTED_H_
+#define BASE_MEMORY_REF_COUNTED_H_
+#pragma once
+
+#include "base/atomic_ref_count.h"
+#include "base/base_export.h"
+#include "base/threading/thread_collision_warner.h"
+
+namespace base {
+
+namespace subtle {
+
+class BASE_EXPORT RefCountedBase {
+ public:
+  static bool ImplementsThreadSafeReferenceCounting() { return false; }
+
+  bool HasOneRef() const { return ref_count_ == 1; }
+
+ protected:
+  RefCountedBase();
+  ~RefCountedBase();
+
+  void AddRef() const;
+
+  // Returns true if the object should self-delete.
+  bool Release() const;
+
+ private:
+  mutable int ref_count_;
+#ifndef NDEBUG
+  mutable bool in_dtor_;
+#endif
+
+  DFAKE_MUTEX(add_release_);
+
+  DISALLOW_COPY_AND_ASSIGN(RefCountedBase);
+};
+
+class BASE_EXPORT RefCountedThreadSafeBase {
+ public:
+  static bool ImplementsThreadSafeReferenceCounting() { return true; }
+
+  bool HasOneRef() const;
+
+ protected:
+  RefCountedThreadSafeBase();
+  ~RefCountedThreadSafeBase();
+
+  void AddRef() const;
+
+  // Returns true if the object should self-delete.
+  bool Release() const;
+
+ private:
+  mutable AtomicRefCount ref_count_;
+#ifndef NDEBUG
+  mutable bool in_dtor_;
+#endif
+
+  DISALLOW_COPY_AND_ASSIGN(RefCountedThreadSafeBase);
+};
+
+}  // namespace subtle
+
+//
+// A base class for reference counted classes.  Otherwise, known as a cheap
+// knock-off of WebKit's RefCounted<T> class.  To use this guy just extend your
+// class from it like so:
+//
+//   class MyFoo : public base::RefCounted<MyFoo> {
+//    ...
+//    private:
+//     friend class base::RefCounted<MyFoo>;
+//     ~MyFoo();
+//   };
+//
+// You should always make your destructor private, to avoid any code deleting
+// the object accidently while there are references to it.
+template <class T>
+class RefCounted : public subtle::RefCountedBase {
+ public:
+  RefCounted() { }
+  ~RefCounted() { }
+
+  void AddRef() const {
+    subtle::RefCountedBase::AddRef();
+  }
+
+  void Release() const {
+    if (subtle::RefCountedBase::Release()) {
+      delete static_cast<const T*>(this);
+    }
+  }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(RefCounted<T>);
+};
+
+// Forward declaration.
+template <class T, typename Traits> class RefCountedThreadSafe;
+
+// Default traits for RefCountedThreadSafe<T>.  Deletes the object when its ref
+// count reaches 0.  Overload to delete it on a different thread etc.
+template<typename T>
+struct DefaultRefCountedThreadSafeTraits {
+  static void Destruct(const T* x) {
+    // Delete through RefCountedThreadSafe to make child classes only need to be
+    // friend with RefCountedThreadSafe instead of this struct, which is an
+    // implementation detail.
+    RefCountedThreadSafe<T,
+                         DefaultRefCountedThreadSafeTraits>::DeleteInternal(x);
+  }
+};
+
+//
+// A thread-safe variant of RefCounted<T>
+//
+//   class MyFoo : public base::RefCountedThreadSafe<MyFoo> {
+//    ...
+//   };
+//
+// If you're using the default trait, then you should add compile time
+// asserts that no one else is deleting your object.  i.e.
+//    private:
+//     friend class base::RefCountedThreadSafe<MyFoo>;
+//     ~MyFoo();
+template <class T, typename Traits = DefaultRefCountedThreadSafeTraits<T> >
+class RefCountedThreadSafe : public subtle::RefCountedThreadSafeBase {
+ public:
+  RefCountedThreadSafe() { }
+  ~RefCountedThreadSafe() { }
+
+  void AddRef() const {
+    subtle::RefCountedThreadSafeBase::AddRef();
+  }
+
+  void Release() const {
+    if (subtle::RefCountedThreadSafeBase::Release()) {
+      Traits::Destruct(static_cast<const T*>(this));
+    }
+  }
+
+ private:
+  friend struct DefaultRefCountedThreadSafeTraits<T>;
+  static void DeleteInternal(const T* x) { delete x; }
+
+  DISALLOW_COPY_AND_ASSIGN(RefCountedThreadSafe);
+};
+
+//
+// A wrapper for some piece of data so we can place other things in
+// scoped_refptrs<>.
+//
+template<typename T>
+class RefCountedData : public base::RefCounted< base::RefCountedData<T> > {
+ public:
+  RefCountedData() : data() {}
+  RefCountedData(const T& in_value) : data(in_value) {}
+
+  T data;
+};
+
+}  // namespace base
+
+//
+// A smart pointer class for reference counted objects.  Use this class instead
+// of calling AddRef and Release manually on a reference counted object to
+// avoid common memory leaks caused by forgetting to Release an object
+// reference.  Sample usage:
+//
+//   class MyFoo : public RefCounted<MyFoo> {
+//    ...
+//   };
+//
+//   void some_function() {
+//     scoped_refptr<MyFoo> foo = new MyFoo();
+//     foo->Method(param);
+//     // |foo| is released when this function returns
+//   }
+//
+//   void some_other_function() {
+//     scoped_refptr<MyFoo> foo = new MyFoo();
+//     ...
+//     foo = NULL;  // explicitly releases |foo|
+//     ...
+//     if (foo)
+//       foo->Method(param);
+//   }
+//
+// The above examples show how scoped_refptr<T> acts like a pointer to T.
+// Given two scoped_refptr<T> classes, it is also possible to exchange
+// references between the two objects, like so:
+//
+//   {
+//     scoped_refptr<MyFoo> a = new MyFoo();
+//     scoped_refptr<MyFoo> b;
+//
+//     b.swap(a);
+//     // now, |b| references the MyFoo object, and |a| references NULL.
+//   }
+//
+// To make both |a| and |b| in the above example reference the same MyFoo
+// object, simply use the assignment operator:
+//
+//   {
+//     scoped_refptr<MyFoo> a = new MyFoo();
+//     scoped_refptr<MyFoo> b;
+//
+//     b = a;
+//     // now, |a| and |b| each own a reference to the same MyFoo object.
+//   }
+//
+template <class T>
+class scoped_refptr {
+ public:
+  scoped_refptr() : ptr_(NULL) {
+  }
+
+  scoped_refptr(T* p) : ptr_(p) {
+    if (ptr_)
+      ptr_->AddRef();
+  }
+
+  scoped_refptr(const scoped_refptr<T>& r) : ptr_(r.ptr_) {
+    if (ptr_)
+      ptr_->AddRef();
+  }
+
+  template <typename U>
+  scoped_refptr(const scoped_refptr<U>& r) : ptr_(r.get()) {
+    if (ptr_)
+      ptr_->AddRef();
+  }
+
+  ~scoped_refptr() {
+    if (ptr_)
+      ptr_->Release();
+  }
+
+  T* get() const { return ptr_; }
+  operator T*() const { return ptr_; }
+  T* operator->() const { return ptr_; }
+
+  // Release a pointer.
+  // The return value is the current pointer held by this object.
+  // If this object holds a NULL pointer, the return value is NULL.
+  // After this operation, this object will hold a NULL pointer,
+  // and will not own the object any more.
+  T* release() {
+    T* retVal = ptr_;
+    ptr_ = NULL;
+    return retVal;
+  }
+
+  scoped_refptr<T>& operator=(T* p) {
+    // AddRef first so that self assignment should work
+    if (p)
+      p->AddRef();
+    if (ptr_ )
+      ptr_ ->Release();
+    ptr_ = p;
+    return *this;
+  }
+
+  scoped_refptr<T>& operator=(const scoped_refptr<T>& r) {
+    return *this = r.ptr_;
+  }
+
+  template <typename U>
+  scoped_refptr<T>& operator=(const scoped_refptr<U>& r) {
+    return *this = r.get();
+  }
+
+  void swap(T** pp) {
+    T* p = ptr_;
+    ptr_ = *pp;
+    *pp = p;
+  }
+
+  void swap(scoped_refptr<T>& r) {
+    swap(&r.ptr_);
+  }
+
+ protected:
+  T* ptr_;
+};
+
+// Handy utility for creating a scoped_refptr<T> out of a T* explicitly without
+// having to retype all the template arguments
+template <typename T>
+scoped_refptr<T> make_scoped_refptr(T* t) {
+  return scoped_refptr<T>(t);
+}
+
+#endif  // BASE_MEMORY_REF_COUNTED_H_