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

components/sync/protocol/proto_value_conversions_unittest.cc

Index: components/sync/protocol/proto_value_conversions_unittest.cc
diff --git a/components/sync/protocol/proto_value_conversions_unittest.cc b/components/sync/protocol/proto_value_conversions_unittest.cc
index 24bf6b120cc1d4996ec31d258f6c49ae8dbbfdac..19b0c8e8963f8cad5c71e4568b4d6290141c5aea 100644
--- a/components/sync/protocol/proto_value_conversions_unittest.cc
+++ b/components/sync/protocol/proto_value_conversions_unittest.cc
@@ -360,9 +360,9 @@ namespace {
 // path.
 bool ValueHasSpecifics(const base::DictionaryValue& value,
                        const std::string& path) {
-  const base::ListValue* entities_list = NULL;
-  const base::DictionaryValue* entry_dictionary = NULL;
-  const base::DictionaryValue* specifics_dictionary = NULL;
+  const base::ListValue* entities_list = nullptr;
+  const base::DictionaryValue* entry_dictionary = nullptr;
+  const base::DictionaryValue* specifics_dictionary = nullptr;
 
   if (!value.GetList(path, &entities_list))
     return false;