Convert NULL to nullptr in transport security state generator.

net/tools/transport_security_state_generator/cert_util.cc

 // Copyright 2016 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 "net/tools/transport_security_state_generator/cert_util.h"
 
 #include <string>
 
 #include "base/base64.h"
 #include "base/files/file_util.h"
@@ skipping 71 matching lines @@
 }  // namespace
 
 bssl::UniquePtr<X509> GetX509CertificateFromPEM(base::StringPiece pem_data) {
   std::string der;
   if (!ParsePEM(pem_data, "CERTIFICATE", &der)) {
     return bssl::UniquePtr<X509>();
   }
 
   const uint8_t* der_data = reinterpret_cast<const uint8_t*>(der.c_str());
   return bssl::UniquePtr<X509>(
-      d2i_X509(NULL, &der_data, base::checked_cast<long>(der.size())));
+      d2i_X509(nullptr, &der_data, base::checked_cast<long>(der.size())));
 }
 
 bool ExtractSubjectNameFromCertificate(X509* certificate, std::string* name) {
   DCHECK(certificate);
   X509_NAME* subject = X509_get_subject_name(certificate);
   if (!subject) {
     return false;
   }
 
   std::string result;
@@ skipping 43 matching lines @@
   std::string der;
   bool result = ParsePEM(pem_key, "PUBLIC KEY", &der);
   if (!result) {
     return false;
   }
 
   out_hash->CalculateFromBytes(reinterpret_cast<const uint8_t*>(der.data()),
                                der.size());
   return true;
 }