use variadic macros/templates in IPC message implementation

ipc/attachment_broker_messages.h

 // Copyright 2015 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.
 
 // IPC messages used by the attachment broker.
 // Multiply-included message file, hence no include guard.
 
 #include "base/process/process_handle.h"
 #include "ipc/brokerable_attachment.h"
 #include "ipc/ipc_export.h"
 #include "ipc/ipc_message_macros.h"
 
 #if defined(OS_WIN)
 #include "ipc/handle_attachment_win.h"
 #endif  // defined(OS_WIN)
 
 #if defined(OS_MACOSX)
 #include "ipc/mach_port_attachment_mac.h"
 #endif  // defined(OS_MACOSX)
 
+#undef IPC_MESSAGE_EXPORT

[danakj, 2015/12/19 00:15:06]

Why is this moved?

[mdempsky, 2015/12/19 02:14:48]

I was trying to fix the Windows component build and thought this was the
problem, though this didn't fix it (at least in isolation).  I'll check if this
can be reverted.

(Context: The IPC_STRUCTS_TRAITS_BEGIN macros define template specializations
using IPC_MESSAGE_EXPORT.  At one point I had Windows component build errors
relating to the messages below (e.g., AttachmentBrokerMsg_DuplicateWinHandle)
referring to PC::internal::HandleAttachmentWin::WireFormat's Traits.  I thought
the problem might have been that the traits specializations and messages were
using different EXPORT settings, so I moved this up so they'd have the same.)

+#define IPC_MESSAGE_EXPORT IPC_EXPORT
+#define IPC_MESSAGE_START AttachmentBrokerMsgStart
+
 // ----------------------------------------------------------------------------
 // Serialization of structs.
 // ----------------------------------------------------------------------------
 
 #if defined(OS_WIN)
 // Define the serialization for Permissions.
 IPC_ENUM_TRAITS_MAX_VALUE(HandleWin::Permissions, HandleWin::MAX_PERMISSIONS);
 
 IPC_STRUCT_TRAITS_BEGIN(IPC::internal::HandleAttachmentWin::WireFormat)
   IPC_STRUCT_TRAITS_MEMBER(handle)
   IPC_STRUCT_TRAITS_MEMBER(destination_process)
   IPC_STRUCT_TRAITS_MEMBER(permissions)
   IPC_STRUCT_TRAITS_MEMBER(attachment_id)
 IPC_STRUCT_TRAITS_END()
 #endif  // defined(OS_WIN)
 
 #if defined(OS_MACOSX)
 IPC_STRUCT_TRAITS_BEGIN(IPC::internal::MachPortAttachmentMac::WireFormat)
   IPC_STRUCT_TRAITS_MEMBER(mach_port)
   IPC_STRUCT_TRAITS_MEMBER(destination_process)
   IPC_STRUCT_TRAITS_MEMBER(attachment_id)
 IPC_STRUCT_TRAITS_END()
 #endif  // defined(OS_MACOSX)
 
-#undef IPC_MESSAGE_EXPORT
-#define IPC_MESSAGE_EXPORT IPC_EXPORT
-#define IPC_MESSAGE_START AttachmentBrokerMsgStart
-
 // ----------------------------------------------------------------------------
 // Messages sent from the broker to a non-broker process.
 // ----------------------------------------------------------------------------
 
 #if defined(OS_WIN)
 // Sent from a broker to a non-broker to indicate that a windows HANDLE has been
 // brokered. Contains all information necessary for the non-broker to translate
 // a BrokerAttachment::AttachmentId to a BrokerAttachment.
 IPC_MESSAGE_CONTROL1(
     AttachmentBrokerMsg_WinHandleHasBeenDuplicated,
@@ skipping 24 matching lines @@
 #endif  // defined(OS_WIN)
 
 #if defined(OS_MACOSX)
 // Sent from a non-broker process to a broker process to request the duplication
 // of a Mach port into a different process (possibly the broker process, or even
 // the original process).
 IPC_MESSAGE_CONTROL1(
     AttachmentBrokerMsg_DuplicateMachPort,
     IPC::internal::MachPortAttachmentMac::WireFormat /* wire_format */)
 #endif  // defined(OS_MACOSX)