ipc: Remove unnecessary attachment broker plumbing.

remoting/host/ipc_util_posix.cc

 // Copyright 2013 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 "remoting/host/ipc_util.h"
 
 #include <fcntl.h>
 #include <sys/socket.h>
 #include <sys/types.h>
 #include <unistd.h>
@@ skipping 29 matching lines @@
       PLOG(ERROR) << "close()";
     return false;
   }
 
   std::string socket_name = "Chromoting socket";
 
   // Wrap the pipe into an IPC channel.
   base::FileDescriptor fd(pipe_fds[0], false);
   IPC::ChannelHandle handle(socket_name, fd);
   *server_out = IPC::ChannelProxy::Create(IPC::ChannelHandle(socket_name, fd),
-                                          IPC::Channel::MODE_SERVER,
-                                          listener,
-                                          io_task_runner.get(),
-                                          nullptr);
+                                          IPC::Channel::MODE_SERVER, listener,
+                                          io_task_runner.get());
 
   *client_out = base::File(pipe_fds[1]);
   return true;
 }
 
 } // namespace remoting