Generate better catalog C++ sources

services/service_manager/public/cpp/test/service_test_catalog.h

 // Copyright 2017 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.
 
+#ifndef SERVICES_SERVICE_MANAGER_PUBLIC_CPP_TEST_SERVICE_TEST_CATALOG_H_
+#define SERVICES_SERVICE_MANAGER_PUBLIC_CPP_TEST_SERVICE_TEST_CATALOG_H_
+
+#include <memory>
+
+namespace base {
+class Value;
+}
+
 namespace service_manager {
 namespace test {
 
-// This symbol must be defined by any target linking against the
+// This function must be defined by any target linking against the
 // ":run_all_service_tests" target in this directory. Use the service_test
 // GN template defined in
 // src/services/service_manager/public/tools/test/service_test.gni to
-// autogenerate and link against a definition of the symbol dervied from the
-// contents of a generated service catalog. See the service_test.gni
-// documentation for more details.
-extern const char kServiceTestCatalog[];
+// autogenerate and link against a definition of the function generated from the
+// contents of a catalog manifest. See the service_test.gni documentation for
+// more details.
+std::unique_ptr<base::Value> CreateTestCatalog();
 
 }  // namespace test
 }  // namespace service_manager
+
+#endif  // SERVICES_SERVICE_MANAGER_PUBLIC_CPP_TEST_SERVICE_TEST_CATALOG_H_