ipc: Make a new class PlaceholderBrokerableAttachment.

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 <stdint.h>
 
 #include "base/process/process_handle.h"
@@ skipping 22 matching lines @@
     // The permissions to use when duplicating the handle.
     HandleWin::Permissions permissions;
     AttachmentId attachment_id;
   };
 
   HandleAttachmentWin(const HANDLE& handle, HandleWin::Permissions permissions);
   explicit HandleAttachmentWin(const WireFormat& wire_format);
   explicit HandleAttachmentWin(const BrokerableAttachment::AttachmentId& id);
 
   BrokerableType GetBrokerableType() const override;
-  void PopulateWithAttachment(const BrokerableAttachment* attachment) override;
 
   // Returns the wire format of this attachment.
   WireFormat GetWireFormat(const base::ProcessId& destination) const;
 
   HANDLE get_handle() const { return handle_; }
 
  private:
   ~HandleAttachmentWin() override;
   HANDLE handle_;
   HandleWin::Permissions permissions_;
 };
 
 }  // namespace internal
 }  // namespace IPC
 
 #endif  // IPC_HANDLE_ATTACHMENT_WIN_H_