ipc: Remove unnecessary attachment broker plumbing.

ipc/ipc_channel_unittest.cc

 // 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.
 
 #include "build/build_config.h"
 
 #if defined(OS_WIN)
 #include <windows.h>
 #endif
 
@@ skipping 149 matching lines @@
   EXPECT_TRUE(WaitForClientShutdown());
   DestroyChannel();
 }
 
 MULTIPROCESS_IPC_TEST_CLIENT_MAIN(GenericClient) {
   base::MessageLoopForIO main_message_loop;
   IPC::TestChannelListener listener;
 
   // Set up IPC channel.
   scoped_ptr<IPC::Channel> channel(IPC::Channel::CreateClient(
-      IPCTestBase::GetChannelName("GenericClient"), &listener, nullptr));
+      IPCTestBase::GetChannelName("GenericClient"), &listener));
   CHECK(channel->Connect());
   listener.Init(channel.get());
   IPC::TestChannelListener::SendOneMessage(channel.get(), "hello from child");
 
   base::MessageLoop::current()->Run();
   return 0;
 }
 
 }  // namespace