Require an explicit ServiceName annotation for interfaces in C++.

services/test_service/test_request_tracker.mojom

Index: services/test_service/test_request_tracker.mojom
diff --git a/services/test_service/test_request_tracker.mojom b/services/test_service/test_request_tracker.mojom
index 91f8a2d444b72719b9dfdb5cb912850cafca277e..0a43e4b6e180717056d75163dbdce96c197ac298 100644
--- a/services/test_service/test_request_tracker.mojom
+++ b/services/test_service/test_request_tracker.mojom
@@ -21,12 +21,14 @@ struct ServiceReport {
 
 // A simple interface to obtain a "report" from all services that have
 // opted to connect themselves to for request tracking.
+[ServiceName="mojo::test::TestTrackedRequestService"]
 interface TestTrackedRequestService {
   GetReport() => (array<ServiceReport?>? report);
 };
 
 // TestRequestTracker records ServiceStats for an individual service
 // connection for aggregation in a TestTrackedRequestService.
+[ServiceName="mojo::test::TestRequestTracker"]
 interface TestRequestTracker {
   SetNameAndReturnId(string service_name) => (uint64 id);
   // Upload a ServiceStats for tracking.