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

shell/application_manager/test.mojom

Index: shell/application_manager/test.mojom
diff --git a/shell/application_manager/test.mojom b/shell/application_manager/test.mojom
index f5a45a8125a1096404e1514332c6c1deed5d79c9..732fe35dd0c5b150de0db81cf9bebd4919dde0b0 100644
--- a/shell/application_manager/test.mojom
+++ b/shell/application_manager/test.mojom
@@ -4,20 +4,24 @@
 
 module shell;
 
+[ServiceName="shell::TestService"]
 interface TestService {
   Test(string test_string) => ();
 };
 
+[ServiceName="shell::TestA"]
 interface TestA {
   CallB();
   CallCFromB();
 };
 
+[ServiceName="shell::TestB"]
 interface TestB {
   B() => ();
   CallC() => ();
 };
 
+[ServiceName="shell::TestC"]
 interface TestC {
   C() => ();
 };