[Sync] Rework Invalidator-related unit tests

sync/internal_api/public/base/model_type_state_map.h

Index: sync/internal_api/public/base/model_type_state_map.h
diff --git a/sync/internal_api/public/base/model_type_state_map.h b/sync/internal_api/public/base/model_type_state_map.h
index 71b0e65fd8c6d8795e0ee9c5f3da521be6c703fe..5a9f84d6fc40eab3c30726d9533ef8512e3a3895 100644
--- a/sync/internal_api/public/base/model_type_state_map.h
+++ b/sync/internal_api/public/base/model_type_state_map.h
@@ -35,14 +35,14 @@ SYNC_EXPORT ModelTypeStateMap ModelTypeSetToStateMap(
     ModelTypeSet model_types, const std::string& payload);
 
 ModelTypeSet ModelTypeStateMapToSet(
-    const ModelTypeStateMap& payload_map);
+    const ModelTypeStateMap& type_state_map);
 
 std::string ModelTypeStateMapToString(
-    const ModelTypeStateMap& model_type_payloads);
+    const ModelTypeStateMap& type_state_map);
 
 // Caller takes ownership of the returned dictionary.
 base::DictionaryValue* ModelTypeStateMapToValue(
-    const ModelTypeStateMap& model_type_payloads);
+    const ModelTypeStateMap& type_state_map);
 
 // Coalesce |update| into |original|, overwriting only when |update| has
 // a non-empty payload.