Switch to standard integer types in tools/.

tools/gn/generate_test_gn_data.cc

 // Copyright (c) 2013 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 <stddef.h>
+
 #include <fstream>
 #include <iostream>
 
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/utf_string_conversions.h"
 #include "build/build_config.h"
 
 // Usage: just run in the directory where you want your test source root to be.
@@ skipping 101 matching lines @@
   }
 }
 
 int main() {
   WriteLevel(std::vector<int>(), 5, 4, 3, 50);  // 781 files, 2343 targets
   //WriteLevel(std::vector<int>(), 6, 4, 2, 50);
   std::cout << "Wrote " << files_written << " files and "
             << targets_written << " targets.\n";
   return 0;
 }