IPC: Add new classes required for attachment brokering.

ipc/handle_attachment_win.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.
+
+#ifndef IPC_HANDLE_ATTACHMENT_WIN_H_
+#define IPC_HANDLE_ATTACHMENT_WIN_H_
+
+#include "ipc/brokerable_attachment.h"
+#include "ipc/ipc_export.h"
+
+namespace IPC {
+namespace internal {
+
+// This class represents a Windows HANDLE attached to a Chrome IPC message.
+class IPC_EXPORT HandleAttachmentWin : public BrokerableAttachment {
+  HANDLE handle_;

[Will Harris, 2015/06/16 12:58:17]

handle_ should be private?

[erikchen, 2015/06/16 17:56:42]

Classes are private by default. 

I added a private: specifier, since if you were confused by this, other people
will be too. I also moved the method before the member variable.

+  Type GetType() const override { return TYPE_WIN_HANDLE; }
+};
+
+}  // namespace internal
+}  // namespace IPC
+
+#endif  // IPC_HANDLE_ATTACHMENT_WIN_H_