IPC: Add attachment brokering support to the message header.

ipc/ipc_test_messages.h

Index: ipc/ipc_test_messages.h
diff --git a/ipc/ipc_test_messages.h b/ipc/ipc_test_messages.h
new file mode 100644
index 0000000000000000000000000000000000000000..ee0c540645660df98c86f40567e0c105c394301f
--- /dev/null
+++ b/ipc/ipc_test_messages.h
@@ -0,0 +1,16 @@
+// 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.
+
+#include "ipc/ipc_message_macros.h"
+
+#if defined(OS_WIN)
+#include "ipc/handle_win.h"
+#endif
+
+#define IPC_MESSAGE_START IPCTestMsgStart
+
+#if defined(OS_WIN)
+IPC_MESSAGE_CONTROL3(TestHandleWinMsg, int, IPC::HandleWin, int)
+IPC_MESSAGE_CONTROL2(TestTwoHandleWinMsg, IPC::HandleWin, IPC::HandleWin)
+#endif