use variadic macros/templates in IPC message implementation

components/nacl/browser/nacl_file_host.cc

Index: components/nacl/browser/nacl_file_host.cc
diff --git a/components/nacl/browser/nacl_file_host.cc b/components/nacl/browser/nacl_file_host.cc
index 0c10254f16302593b859f938ad12fbe4b0c06501..36c9eba66fbfb0017593906cd1f9361db19805bb 100644
--- a/components/nacl/browser/nacl_file_host.cc
+++ b/components/nacl/browser/nacl_file_host.cc
@@ -43,9 +43,9 @@ void NotifyRendererOfError(
 }
 
 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,

[vmpstr, 2016/02/04 23:43:26]

Why this change?

[mdempsky, 2016/02/05 00:32:32]

Previously MySyncMessage::WriteReplyParams was a templated member function that
took any parameter types, but then always converted them to "const T&".  In this
CL I changed it to simply take "const T&" arguments directly.

Most WriteReplyParams users simply called it directly and were unaffected, but
this file use a function-pointer to indirectly call one of a couple different
WriteReplyParams functions.  Because it's no longer templated though, the
static_cast<WriteFileInfoReply> can't force a particular template instantiation
anymore.  Hence changing this type.

+                                   const uint64_t& file_token_hi);
 
 void DoRegisterOpenedNaClExecutableFile(
     scoped_refptr<nacl::NaClHostMessageFilter> nacl_host_message_filter,