use variadic macros/templates in IPC message implementation

components/nacl/browser/nacl_file_host.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/nacl/browser/nacl_file_host.h"
 
 #include <stddef.h>
 #include <stdint.h>
 #include <utility>
 
@@ skipping 25 matching lines @@
 const size_t kMaxFileLength = 40;
 
 void NotifyRendererOfError(
     nacl::NaClHostMessageFilter* nacl_host_message_filter,
     IPC::Message* reply_msg) {
   reply_msg->set_reply_error();
   nacl_host_message_filter->Send(reply_msg);
 }
 
 typedef void (*WriteFileInfoReply)(IPC::Message* reply_msg,
-                                   IPC::PlatformFileForTransit file_desc,
-                                   uint64_t file_token_lo,
-                                   uint64_t file_token_hi);
+                                   const IPC::PlatformFileForTransit& file_desc,
+                                   const uint64_t& file_token_lo,
+                                   const uint64_t& file_token_hi);
 
 void DoRegisterOpenedNaClExecutableFile(
     scoped_refptr<nacl::NaClHostMessageFilter> nacl_host_message_filter,
     base::File file,
     base::FilePath file_path,
     IPC::Message* reply_msg,
     WriteFileInfoReply write_reply_message) {
   // IO thread owns the NaClBrowser singleton.
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
 
@@ skipping 213 matching lines @@
           &DoOpenNaClExecutableOnThreadPool,
           nacl_host_message_filter,
           file_url,
           enable_validation_caching,
           reply_msg))) {
     NotifyRendererOfError(nacl_host_message_filter.get(), reply_msg);
   }
 }
 
 }  // namespace nacl_file_host