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

components/sync/syncable/change_record_unittest.cc

 // Copyright (c) 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/syncable/change_record.h"
 
 #include <stddef.h>
 
 #include <string>
 #include <utility>
@@ skipping 39 matching lines @@
 
 void CheckChangeRecordValue(const ChangeRecord& record,
                             const base::DictionaryValue& value) {
   ExpectChangeRecordActionValue(record.action, value, "action");
   ExpectDictStringValue(base::Int64ToString(record.id), value, "id");
   if (record.action == ChangeRecord::ACTION_DELETE) {
     std::unique_ptr<base::DictionaryValue> expected_extra_value;
     if (record.extra.get()) {
       expected_extra_value = record.extra->ToValue();
     }
-    const base::Value* extra_value = NULL;
-    EXPECT_EQ(record.extra.get() != NULL, value.Get("extra", &extra_value));
+    const base::Value* extra_value = nullptr;
+    EXPECT_EQ(record.extra.get() != nullptr, value.Get("extra", &extra_value));
     EXPECT_TRUE(base::Value::Equals(extra_value, expected_extra_value.get()));
 
     std::unique_ptr<base::DictionaryValue> expected_specifics_value(
         EntitySpecificsToValue(record.specifics));
     ExpectDictDictionaryValue(*expected_specifics_value, value, "specifics");
   }
 }
 
 class TestExtraChangeRecordData : public ExtraPasswordChangeRecordData {
  public:
@@ skipping 79 matching lines @@
     extra->set_expected_to_value_calls(2U);
 
     record.extra.reset(extra.release());
     std::unique_ptr<base::DictionaryValue> value(record.ToValue());
     CheckChangeRecordValue(record, *value);
   }
 }
 
 }  // namespace
 }  // namespace syncer