add internal_access option for C# codegen
diff --git a/src/compiler/csharp_plugin.cc b/src/compiler/csharp_plugin.cc
index fd1ec99..5350e73 100644
--- a/src/compiler/csharp_plugin.cc
+++ b/src/compiler/csharp_plugin.cc
@@ -53,11 +53,14 @@
 
     bool generate_client = true;
     bool generate_server = true;
+    bool internal_access = false;
     for (size_t i = 0; i < options.size(); i++) {
       if (options[i].first == "no_client") {
         generate_client = false;
       } else if (options[i].first == "no_server") {
         generate_server = false;
+      } else if (options[i].first == "internal_access") {
+        internal_access = true;
       } else {
         *error = "Unknown generator option: " + options[i].first;
         return false;
@@ -66,7 +69,8 @@
 
     grpc::string code = grpc_csharp_generator::GetServices(file,
                                                            generate_client,
-                                                           generate_server);
+                                                           generate_server,
+                                                           internal_access);
     if (code.size() == 0) {
       return true;  // don't generate a file if there are no services
     }