Splitting interop_server.cc
diff --git a/test/cpp/interop/server_helper.h b/test/cpp/interop/server_helper.h
index a1da14a..fc4ea8b3e 100644
--- a/test/cpp/interop/server_helper.h
+++ b/test/cpp/interop/server_helper.h
@@ -60,6 +60,12 @@
   const ::grpc::ServerContext& context_;
 };
 
+namespace interop {
+
+extern bool g_got_sigint;
+void RunServer(std::shared_ptr<ServerCredentials> creds);
+
+}  // namespace interop
 }  // namespace testing
 }  // namespace grpc