use variadic macros/templates in IPC message implementation

ipc/BUILD.gn

 # 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.
 
 import("//build/config/nacl/config.gni")
 import("//testing/test.gni")
 
 component("ipc") {
   sources = [
     "attachment_broker.cc",
@@ skipping 47 matching lines @@
     "ipc_message.cc",
     "ipc_message.h",
     "ipc_message_attachment.cc",
     "ipc_message_attachment.h",
     "ipc_message_attachment_set.cc",
     "ipc_message_attachment_set.h",
     "ipc_message_generator.cc",
     "ipc_message_generator.h",
     "ipc_message_macros.h",
     "ipc_message_start.h",
+    "ipc_message_templates.h",
+    "ipc_message_templates_impl.h",
     "ipc_message_utils.cc",
     "ipc_message_utils.h",
     "ipc_platform_file.cc",
     "ipc_platform_file.h",
     "ipc_platform_file_attachment_posix.cc",
     "ipc_platform_file_attachment_posix.h",
     "ipc_sender.h",
     "ipc_switches.cc",
     "ipc_switches.h",
     "ipc_sync_channel.cc",
@@ skipping 173 matching lines @@
   ]
   public_deps = [
     ":ipc",
   ]
   deps = [
     "//base",
     "//base/test:test_support",
     "//testing/gtest",
   ]
 }