Make HttpService.Echo in example/http_c++ as http service again

example/http_c++/http.proto

@@ -3,12 +3,8 @@ package example;
 
 option cc_generic_services = true;
 
-message HttpRequest { 
-  optional bytes message = 1;
-};
-message HttpResponse {
-  optional bytes message = 1;
-};
+message HttpRequest {};
+message HttpResponse {};
 
 service HttpService {
   rpc Echo(HttpRequest) returns (HttpResponse);

example/http_c++/http_server.cpp

@@ -58,16 +58,6 @@ public:
         os << "\nbody: " << cntl->request_attachment() << '\n';
         os.move_to(cntl->response_attachment());
     }
-
-    void EchoProtobuf(google::protobuf::RpcController*,
-                      const HttpRequest* request,
-                      HttpResponse* response,
-                      google::protobuf::Closure* done) {
-        // This object helps you to call done->Run() in RAII style. If you need
-        // to process the request asynchronously, pass done_guard.release().
-        brpc::ClosureGuard done_guard(done);
-        response->set_message(request->message());
-    }
 };
 
 // Service with dynamic path.