Revert of Remove a scoped_refptr<>::swap overload

base/memory/ref_counted.h

 // Copyright (c) 2012 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_
 
 #include <stddef.h>
 
-#include <algorithm>
 #include <cassert>
 #include <iosfwd>
 #include <type_traits>
 
 #include "base/atomic_ref_count.h"
 #include "base/base_export.h"
 #include "base/compiler_specific.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/threading/thread_collision_warner.h"
@@ skipping 327 matching lines @@
     scoped_refptr<T>(std::move(r)).swap(*this);
     return *this;
   }
 
   template <typename U>
   scoped_refptr<T>& operator=(scoped_refptr<U>&& r) {
     scoped_refptr<T>(std::move(r)).swap(*this);
     return *this;
   }
 
-  void swap(scoped_refptr<T>& r) { std::swap(ptr_, r.ptr_); }
+  void swap(T** pp) {
+    T* p = ptr_;
+    ptr_ = *pp;
+    *pp = p;
+  }
+
+  void swap(scoped_refptr<T>& r) {
+    swap(&r.ptr_);
+  }
 
   explicit operator bool() const { return ptr_ != nullptr; }
 
   template <typename U>
   bool operator==(const scoped_refptr<U>& rhs) const {
     return ptr_ == rhs.get();
   }
 
   template <typename U>
   bool operator!=(const scoped_refptr<U>& rhs) const {
@@ skipping 79 matching lines @@
 bool operator!=(std::nullptr_t null, const scoped_refptr<T>& rhs) {
   return !operator==(null, rhs);
 }
 
 template <typename T>
 std::ostream& operator<<(std::ostream& out, const scoped_refptr<T>& p) {
   return out << p.get();
 }
 
 #endif  // BASE_MEMORY_REF_COUNTED_H_