Convert NULL to nullptr

tools/on_demand_service_tool.mm

 // 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 64 matching lines @@
     kOptionVersion = -3,
   };
 
   struct {
     Operation operation;
     std::string job_label;
     std::vector<std::string> mach_services;
   } options = {};
 
   const struct option long_options[] = {
-      {"load", no_argument, NULL, kOptionLoadJob},
-      {"unload", no_argument, NULL, kOptionUnloadJob},
-      {"label", required_argument, NULL, kOptionJobLabel},
-      {"mach_service", required_argument, NULL, kOptionMachService},
-      {"help", no_argument, NULL, kOptionHelp},
-      {"version", no_argument, NULL, kOptionVersion},
-      {NULL, 0, NULL, 0},
+      {"load", no_argument, nullptr, kOptionLoadJob},
+      {"unload", no_argument, nullptr, kOptionUnloadJob},
+      {"label", required_argument, nullptr, kOptionJobLabel},
+      {"mach_service", required_argument, nullptr, kOptionMachService},
+      {"help", no_argument, nullptr, kOptionHelp},
+      {"version", no_argument, nullptr, kOptionVersion},
+      {nullptr, 0, nullptr, 0},
   };
 
   int opt;
-  while ((opt = getopt_long(argc, argv, "+LUl:m:", long_options, NULL)) != -1) {
+  while ((opt = getopt_long(argc, argv, "+LUl:m:", long_options, nullptr)) !=
+          -1) {
     switch (opt) {
       case kOptionLoadJob:
         options.operation = kOperationLoadJob;
         break;
       case kOptionUnloadJob:
         options.operation = kOperationUnloadJob;
         break;
       case kOptionJobLabel:
         options.job_label = optarg;
         break;
       case kOptionMachService:
         options.mach_services.push_back(optarg);
         break;
       case kOptionHelp:
         Usage(me);
         return EXIT_SUCCESS;
       case kOptionVersion:
         ToolSupport::Version(me);
         return EXIT_SUCCESS;
       default:
-        ToolSupport::UsageHint(me, NULL);
+        ToolSupport::UsageHint(me, nullptr);
         return EXIT_FAILURE;
     }
   }
   argc -= optind;
   argv += optind;
 
   if (options.job_label.empty()) {
     ToolSupport::UsageHint(me, "must provide -l");
     return EXIT_FAILURE;
   }
@@ skipping 60 matching lines @@
     }
   }
 }
 
 }  // namespace
 }  // namespace crashpad
 
 int main(int argc, char* argv[]) {
   return crashpad::OnDemandServiceToolMain(argc, argv);
 }