Adds equality operators for comparing scoped_refptr with nullptr.

base/memory/ref_counted_unittest.cc

 // 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.
 
 #include "base/memory/ref_counted.h"
 
 #include "base/test/opaque_ref_counted.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace {
@@ skipping 186 matching lines @@
   scoped_refptr<SelfAssign> p1(new SelfAssign);
   scoped_refptr<SelfAssign> p2(new SelfAssign);
 
   EXPECT_EQ(p1, p1);
   EXPECT_EQ(p2, p2);
 
   EXPECT_NE(p1, p2);
   EXPECT_NE(p2, p1);
 }
 
+TEST(RefCountedUnitTest, NullptrEquality) {
+  scoped_refptr<SelfAssign> ptr_to_an_instance(new SelfAssign);
+  scoped_refptr<SelfAssign> null_ptr;

[danakj, 2016/05/18 01:12:34]

nit: ptr_to_nullptr might be easier to read here

[Rob Percival, 2016/05/18 01:17:01]

Done.

+
+  EXPECT_NE(nullptr, ptr_to_an_instance);
+  EXPECT_NE(ptr_to_an_instance, nullptr);
+  EXPECT_EQ(nullptr, null_ptr);
+  EXPECT_EQ(null_ptr, nullptr);
+}
+
 TEST(RefCountedUnitTest, ConvertibleEquality) {
   scoped_refptr<Derived> p1(new Derived);
   scoped_refptr<SelfAssign> p2;
 
   EXPECT_NE(p1, p2);
   EXPECT_NE(p2, p1);
 
   p2 = p1;
 
   EXPECT_EQ(p1, p2);
@@ skipping 271 matching lines @@
 
 TEST(RefCountedUnitTest, TestOverloadResolutionMove) {
   scoped_refptr<Derived> derived(new Derived);
   scoped_refptr<SelfAssign> expected(derived);
   EXPECT_EQ(expected, Overloaded(std::move(derived)));
 
   scoped_refptr<Other> other(new Other);
   scoped_refptr<Other> other2(other);
   EXPECT_EQ(other2, Overloaded(std::move(other)));
 }