Adds equality operators for comparing scoped_refptr with nullptr.

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 <cassert>
 #include <iosfwd>
 #include <type_traits>
 
 #include "base/atomic_ref_count.h"
 #include "base/base_export.h"
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #ifndef NDEBUG
 #include "base/logging.h"
@@ skipping 416 matching lines @@
 template <typename T, typename U>
 bool operator==(const scoped_refptr<T>& lhs, const U* rhs) {
   return lhs.get() == rhs;
 }
 
 template <typename T, typename U>
 bool operator==(const T* lhs, const scoped_refptr<U>& rhs) {
   return lhs == rhs.get();
 }
 
+template <typename T>
+bool operator==(const scoped_refptr<T>& lhs, std::nullptr_t null) {
+  return !static_cast<bool>(lhs);
+}
+
+template <typename T>
+bool operator==(std::nullptr_t null, const scoped_refptr<T>& rhs) {
+  return !static_cast<bool>(rhs);
+}
+
 template <typename T, typename U>
 bool operator!=(const scoped_refptr<T>& lhs, const U* rhs) {
   return !operator==(lhs, rhs);
 }
 
 template <typename T, typename U>
 bool operator!=(const T* lhs, const scoped_refptr<U>& rhs) {
   return !operator==(lhs, rhs);
 }
 
 template <typename T>
+bool operator!=(const scoped_refptr<T>& lhs, std::nullptr_t null) {
+  return !operator==(lhs, null);
+}
+
+template <typename T>
+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_