C++11 declares a type safe null pointer

content/common/shareable_file_reference_unittest.cc

 // Copyright 2014 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 "storage/common/blob/shareable_file_reference.h"
 
 #include "base/files/file_util.h"
 #include "base/files/scoped_temp_dir.h"
 #include "base/message_loop/message_loop_proxy.h"
 #include "base/run_loop.h"
@@ skipping 26 matching lines @@
 
   // Get a second reference to that file.
   scoped_refptr<ShareableFileReference> reference2;
   reference2 = ShareableFileReference::Get(file);
   EXPECT_EQ(reference1.get(), reference2.get());
   reference2 = ShareableFileReference::GetOrCreate(
       file, ShareableFileReference::DELETE_ON_FINAL_RELEASE, loop_proxy.get());
   EXPECT_EQ(reference1.get(), reference2.get());
 
   // Drop the first reference, the file and reference should still be there.
-  reference1 = NULL;
+  reference1 = nullptr;
   EXPECT_TRUE(ShareableFileReference::Get(file).get());
   base::RunLoop().RunUntilIdle();
   EXPECT_TRUE(base::PathExists(file));
 
   // Drop the second reference, the file and reference should get deleted.
-  reference2 = NULL;
+  reference2 = nullptr;
   EXPECT_FALSE(ShareableFileReference::Get(file).get());
   base::RunLoop().RunUntilIdle();
   EXPECT_FALSE(base::PathExists(file));
 
   // TODO(michaeln): add a test for files that aren't deletable behavior.
 }
 
 }  // namespace content