sync: Add pre-commit update avoidance mode + flag

sync/internal_api/test/test_internal_components_factory.cc

Index: sync/internal_api/test/test_internal_components_factory.cc
diff --git a/sync/internal_api/test/test_internal_components_factory.cc b/sync/internal_api/test/test_internal_components_factory.cc
index beb249e743d01ae19d2fd267fa8e7bb90a0736e8..154c58cc99a2a96dff87b78fbbbae8c7ddf891bc 100644
--- a/sync/internal_api/test/test_internal_components_factory.cc
+++ b/sync/internal_api/test/test_internal_components_factory.cc
@@ -45,6 +45,8 @@ TestInternalComponentsFactory::BuildContext(
           empty_listeners, debug_info_getter,
           traffic_recorder,
           switches_.encryption_method == ENCRYPTION_KEYSTORE,
+          switches_.pre_commit_updates_policy ==
+              FORCE_ENABLE_PRE_COMMIT_UPDATE_AVOIDANCE,
           invalidator_client_id));
 
 }