Revert of Delete rtc::linked_ptr. Only use, in statstypes.h, replaced bu std::unique_ptr.

webrtc/base/linked_ptr.h

Index: webrtc/base/linked_ptr.h
diff --git a/webrtc/base/linked_ptr.h b/webrtc/base/linked_ptr.h
new file mode 100644
index 0000000000000000000000000000000000000000..65e5a00ecfa75fec7389445122c0fd17f0c64dc5
--- /dev/null
+++ b/webrtc/base/linked_ptr.h
@@ -0,0 +1,125 @@
+/*
+ *  Copyright 2004 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.
+ */
+
+/*
+ * linked_ptr - simple reference linked pointer
+ * (like reference counting, just using a linked list of the references
+ * instead of their count.)
+ *
+ * The implementation stores three pointers for every linked_ptr, but
+ * does not allocate anything on the free store.
+ */
+
+#ifndef WEBRTC_BASE_LINKED_PTR_H__
+#define WEBRTC_BASE_LINKED_PTR_H__
+
+namespace rtc {
+
+/* For ANSI-challenged compilers, you may want to #define
+ * NO_MEMBER_TEMPLATES, explicit or mutable */
+#define NO_MEMBER_TEMPLATES
+
+template <class X> class linked_ptr
+{
+public:
+
+#ifndef NO_MEMBER_TEMPLATES
+#   define TEMPLATE_FUNCTION template <class Y>
+    TEMPLATE_FUNCTION friend class linked_ptr<Y>;
+#else
+#   define TEMPLATE_FUNCTION
+    typedef X Y;
+#endif
+
+    typedef X element_type;
+
+    explicit linked_ptr(X* p = 0) throw()
+        : itsPtr(p) {itsPrev = itsNext = this;}
+    ~linked_ptr()
+        {release();}
+    linked_ptr(const linked_ptr& r) throw()
+        {acquire(r);}
+    linked_ptr& operator=(const linked_ptr& r)
+    {
+        if (this != &r) {
+            release();
+            acquire(r);
+        }
+        return *this;
+    }
+
+#ifndef NO_MEMBER_TEMPLATES
+    template <class Y> friend class linked_ptr<Y>;
+    template <class Y> linked_ptr(const linked_ptr<Y>& r) throw()
+        {acquire(r);}
+    template <class Y> linked_ptr& operator=(const linked_ptr<Y>& r)
+    {
+        if (this != &r) {
+            release();
+            acquire(r);
+        }
+        return *this;
+    }
+#endif // NO_MEMBER_TEMPLATES
+
+    X& operator*()  const throw()   {return *itsPtr;}
+    X* operator->() const throw()   {return itsPtr;}
+    X* get()        const throw()   {return itsPtr;}
+    bool unique()   const throw()   {return itsPrev ? itsPrev==this : true;}
+
+private:
+    X*                          itsPtr;
+    mutable const linked_ptr*   itsPrev;
+    mutable const linked_ptr*   itsNext;
+
+    void acquire(const linked_ptr& r) throw()
+    { // insert this to the list
+        itsPtr = r.itsPtr;
+        itsNext = r.itsNext;
+        itsNext->itsPrev = this;
+        itsPrev = &r;
+#ifndef mutable
+        r.itsNext = this;
+#else // for ANSI-challenged compilers
+        (const_cast<linked_ptr<X>*>(&r))->itsNext = this;
+#endif
+    }
+
+#ifndef NO_MEMBER_TEMPLATES
+    template <class Y> void acquire(const linked_ptr<Y>& r) throw()
+    { // insert this to the list
+        itsPtr = r.itsPtr;
+        itsNext = r.itsNext;
+        itsNext->itsPrev = this;
+        itsPrev = &r;
+#ifndef mutable
+        r.itsNext = this;
+#else // for ANSI-challenged compilers
+        (const_cast<linked_ptr<X>*>(&r))->itsNext = this;
+#endif
+    }
+#endif // NO_MEMBER_TEMPLATES
+
+    void release()
+    { // erase this from the list, delete if unique
+        if (unique()) delete itsPtr;
+        else {
+            itsPrev->itsNext = itsNext;
+            itsNext->itsPrev = itsPrev;
+            itsPrev = itsNext = 0;
+        }
+        itsPtr = 0;
+    }
+};
+
+} // namespace rtc
+
+#endif // WEBRTC_BASE_LINKED_PTR_H__
+