Add support for Attachment Brokering of IPC::Channels on multiple threads.

ipc/attachment_broker_mac_unittest.cc

 // 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.
 
 #include "build/build_config.h"
 
 #include <fcntl.h>
 #include <mach/mach_vm.h>
 #include <stddef.h>
 #include <sys/mman.h>
@@ skipping 545 matching lines @@
   LOG(INFO) << "Privileged process start.";
   scoped_ptr<ChildProcessGlobals> globals(CommonChildProcessSetUp());
 
   mach_msg_type_number_t active_names_at_start = IPC::GetActiveNameCount();
 
   base::MessageLoopForIO main_message_loop;
   ProxyListener listener;
 
   scoped_ptr<IPC::Channel> channel(IPC::Channel::CreateClient(
       IPCTestBase::GetChannelName(channel_name), &listener));
-  globals->broker->RegisterCommunicationChannel(channel.get());
+  globals->broker->RegisterCommunicationChannel(channel.get(), nullptr);
   CHECK(channel->Connect());
 
   globals->initial_resident_size = GetResidentSize();
 
   while (true) {
     if (globals->message_logging)
       LOG(INFO) << "Privileged process spinning run loop.";
     base::MessageLoop::current()->Run();
     ProxyListener::Reason reason = listener.get_reason();
     if (reason == ProxyListener::CHANNEL_ERROR)
@@ skipping 751 matching lines @@
     SendControlMessage(sender, success);
   }
 }
 
 MULTIPROCESS_IPC_TEST_CLIENT_MAIN(MemoryUsageManyMessages) {
   return CommonPrivilegedProcessMain(&MemoryUsageManyMessagesCallback,
                                      "MemoryUsageManyMessages");
 }
 
 }  // namespace