chromium之ref_counted

namespace subtle {

class RefCountedBase {

 protected:

  RefCountedBase();

  ~RefCountedBase();

  void AddRef();

  // Returns true if the object should self-delete.

  bool Release();

 private:

  int ref_count_;

#ifndef NDEBUG

  bool in_dtor_;

#endif

  DFAKE_MUTEX(add_release_);

  DISALLOW_COPY_AND_ASSIGN(RefCountedBase);

};

}；

//

// 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> {

//    ...

//   };

//

template <class T>

class RefCounted : public subtle::RefCountedBase {

 public:

  RefCounted() { }

  ~RefCounted() { }

  void AddRef() {

    subtle::RefCountedBase::AddRef();

  }

  void Release() {

    if (subtle::RefCountedBase::Release()) {

      delete static_cast<T*>(this);

    }

  }

 private:

  DISALLOW_COPY_AND_ASSIGN(RefCounted<T>);

};

截取的代码有两个类，分别是subtle::RefCountedBase，RefCounted。
第一个类subtle::RefCountedBase没有Public方法，只有protected和Private方法。
protected里面有两个方法，一个是AddRef，另一个是Release，伪代码如下

obj->AddRef();

bool needDeleteSelf = obj->Release();

if (needDeleteSelf) {

    delete obj;

}

第二个类RefCounted 是个模板，继承了subtle::RefCountedBase，而且有Public方法

使用方法更简单

class MyFoo : public base::RefCounted<MyFoo> {

};

MyFoo *foo = new MyFoo;

foo->AddRef();

foo->Release();

// foo has been delete