ipc: Create an unforgeable mechanism to get the process id of the sender.

ipc/attachment_broker_privileged_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_ATTACHMENT_BROKER_PRIVILEGED_WIN_H_
 #define IPC_ATTACHMENT_BROKER_PRIVILEGED_WIN_H_
 
 #include <vector>
 
 #include "ipc/attachment_broker.h"
@@ skipping 23 matching lines @@
   // Each unprivileged process should have one IPC channel on which it
   // communicates attachment information with this privileged process. These
   // channels must be registered and deregistered with the Attachment Broker as
   // they are created and destroyed.
   void RegisterCommunicationChannel(Channel* channel);
   void DeregisterCommunicationChannel(Channel* channel);
 
  private:
   using HandleWireFormat = internal::HandleAttachmentWin::WireFormat;
   // IPC message handlers.
-  void OnDuplicateWinHandle(const HandleWireFormat& wire_format,
-                            base::ProcessId source_process);
+  void OnDuplicateWinHandle(const IPC::Message& message);
 
   // Duplicates |wire_Format| from |source_process| into its destination
   // process.
   HandleWireFormat DuplicateWinHandle(const HandleWireFormat& wire_format,
                                       base::ProcessId source_process);
 
   // If the HANDLE's destination is this process, queue it and notify the
   // observers. Otherwise, send it in an IPC to its destination.
   void RouteDuplicatedHandle(const HandleWireFormat& wire_format);
 
   std::vector<Channel*> channels_;
   DISALLOW_COPY_AND_ASSIGN(AttachmentBrokerPrivilegedWin);
 };
 
 }  // namespace IPC
 
 #endif  // IPC_ATTACHMENT_BROKER_PRIVILEGED_WIN_H_