Implement concrete class RefCountedBase.

webrtc/rtc_base/refcountedobject.h

 /*
  *  Copyright 2016 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 #ifndef WEBRTC_RTC_BASE_REFCOUNTEDOBJECT_H_
 #define WEBRTC_RTC_BASE_REFCOUNTEDOBJECT_H_
 
 #include <utility>
 
 #include "webrtc/rtc_base/atomicops.h"
 
 namespace rtc {
 
-template <class T>
-class RefCountedObject : public T {
+// Concrete base class with inline and non-virtual AddRef and Release.
+class RefCountedBase {
  public:
-  RefCountedObject() {}
+  int AddRef() const { return AtomicOps::Increment(&ref_count_); }
 
-  template <class P0>
-  explicit RefCountedObject(P0&& p0) : T(std::forward<P0>(p0)) {}
-
-  template <class P0, class P1, class... Args>
-  RefCountedObject(P0&& p0, P1&& p1, Args&&... args)
-      : T(std::forward<P0>(p0),
-          std::forward<P1>(p1),
-          std::forward<Args>(args)...) {}
-
-  virtual int AddRef() const { return AtomicOps::Increment(&ref_count_); }
-
-  virtual int Release() const {
+  int Release() const {
     int count = AtomicOps::Decrement(&ref_count_);
     if (!count) {
       delete this;
     }
     return count;
   }
 
   // Return whether the reference count is one. If the reference count is used
   // in the conventional way, a reference count of 1 implies that the current
   // thread owns the reference and no other thread shares it. This call
   // performs the test for a reference count of one, and performs the memory
   // barrier needed for the owning thread to act on the object, knowing that it
   // has exclusive access to the object.
-  virtual bool HasOneRef() const {
+  bool HasOneRef() const {
     return AtomicOps::AcquireLoad(&ref_count_) == 1;
   }
 
  protected:
-  virtual ~RefCountedObject() {}
+  virtual ~RefCountedBase() = default;
 
   mutable volatile int ref_count_ = 0;
 };
 
+template <class T>
+class RefCountedObject : public T, protected virtual RefCountedBase {
+ public:
+  RefCountedObject() {}
+
+  template <class P0>
+  explicit RefCountedObject(P0&& p0) : T(std::forward<P0>(p0)) {}
+
+  template <class P0, class P1, class... Args>
+  RefCountedObject(P0&& p0, P1&& p1, Args&&... args)
+      : T(std::forward<P0>(p0),
+          std::forward<P1>(p1),
+          std::forward<Args>(args)...) {}
+
+  virtual int AddRef() const { return RefCountedBase::AddRef(); }
+  virtual int Release() const { return RefCountedBase::Release(); }
+  virtual bool HasOneRef() const { return RefCountedBase::HasOneRef(); }
+
+ protected:
+  virtual ~RefCountedObject() = default;
+};
+
 }  // namespace rtc
 
 #endif  // WEBRTC_RTC_BASE_REFCOUNTEDOBJECT_H_