history_service_   29 chrome/browser/autocomplete/extension_app_provider_unittest.cc         history_service_(NULL) { }
history_service_  398 chrome/browser/browsing_data/browsing_data_remover_unittest.cc   RemoveHistoryTester() : query_url_success_(false), history_service_(NULL) {}
history_service_   88 chrome/browser/sync/glue/history_model_worker.cc     history_service_(history_service) {