[Sync] Replacing NULL with nullptr in code and null in comments for components/sync/

components/sync/engine_impl/sync_encryption_handler_impl.cc

 // Copyright 2012 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 "components/sync/engine_impl/sync_encryption_handler_impl.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <memory>
@@ skipping 154 matching lines @@
     return false;
   }
   std::string decrypted_keystore_bootstrap;
   if (!encryptor->DecryptString(base64_decoded_keystore_bootstrap,
                                 &decrypted_keystore_bootstrap)) {
     return false;
   }
 
   JSONStringValueDeserializer json(decrypted_keystore_bootstrap);
   std::unique_ptr<base::Value> deserialized_keystore_keys(
-      json.Deserialize(NULL, NULL));
+      json.Deserialize(nullptr, nullptr));
   if (!deserialized_keystore_keys)
     return false;
-  base::ListValue* internal_list_value = NULL;
+  base::ListValue* internal_list_value = nullptr;
   if (!deserialized_keystore_keys->GetAsList(&internal_list_value))
     return false;
   int number_of_keystore_keys = internal_list_value->GetSize();
   if (!internal_list_value->GetString(number_of_keystore_keys - 1,
                                       current_keystore_key)) {
     return false;
   }
   old_keystore_keys->resize(number_of_keystore_keys - 1);
   for (int i = 0; i < number_of_keystore_keys - 1; ++i)
     internal_list_value->GetString(i, &(*old_keystore_keys)[i]);
@@ skipping 1489 matching lines @@
 base::Time SyncEncryptionHandlerImpl::GetExplicitPassphraseTime(
     PassphraseType passphrase_type) const {
   if (passphrase_type == PassphraseType::FROZEN_IMPLICIT_PASSPHRASE)
     return migration_time();
   else if (passphrase_type == PassphraseType::CUSTOM_PASSPHRASE)
     return custom_passphrase_time();
   return base::Time();
 }
 
 }  // namespace syncer