Make IPC channels track their peer process ID

ipc/ipc_channel.h

 // Copyright (c) 2012 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_IPC_CHANNEL_H_
 #define IPC_IPC_CHANNEL_H_
 #pragma once
 
 #include <string>
 
 #include "base/compiler_specific.h"
+#include "base/process.h"
 #include "ipc/ipc_channel_handle.h"
 #include "ipc/ipc_message.h"
 
 namespace IPC {
 
 //------------------------------------------------------------------------------
 // See
 // http://www.chromium.org/developers/design-documents/inter-process-communication
 // for overview of IPC in Chromium.
 
@@ skipping 120 matching lines @@
   // Close this Channel explicitly.  May be called multiple times.
   // On POSIX calling close on an IPC channel that listens for connections will
   // cause it to close any accepted connections, and it will stop listening for
   // new connections. If you just want to close the currently accepted
   // connection and listen for new ones, use ResetToAcceptingConnectionState.
   void Close();
 
   // Modify the Channel's listener.
   void set_listener(Listener* listener);
 
+  // Get the process ID for the connected peer.
+  // Returns base::kNullProcessId if the peer is not connected yet.
+  base::ProcessId peer_pid() const;
+
   // Send a message over the Channel to the listener on the other end.
   //
   // |message| must be allocated using operator new.  This object will be
   // deleted once the contents of the Message have been sent.
   virtual bool Send(Message* message) OVERRIDE;
 
 #if defined(OS_POSIX) && !defined(OS_NACL)
   // On POSIX an IPC::Channel wraps a socketpair(), this method returns the
   // FD # for the client end of the socket.
   // This method may only be called on the server side of a channel.
@@ skipping 55 matching lines @@
 
  private:
   // PIMPL to which all channel calls are delegated.
   class ChannelImpl;
   ChannelImpl *channel_impl_;
 };
 
 }  // namespace IPC
 
 #endif  // IPC_IPC_CHANNEL_H_