Convert NULL to nullptr

util/test/multiprocess_exec_test.cc

 // Copyright 2014 The Crashpad Authors. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
@@ skipping 30 matching lines @@
   }
 
   DISALLOW_COPY_AND_ASSIGN(TestMultiprocessExec);
 };
 
 TEST(MultiprocessExec, MultiprocessExec) {
   TestMultiprocessExec multiprocess_exec;
   base::FilePath test_executable = ExecutablePath();
   std::string child_test_executable =
       test_executable.value() + "_multiprocess_exec_test_child";
-  multiprocess_exec.SetChildCommand(child_test_executable, NULL);
+  multiprocess_exec.SetChildCommand(child_test_executable, nullptr);
   multiprocess_exec.Run();
 }
 
 }  // namespace
 }  // namespace test
 }  // namespace crashpad