[mojo-edk] Stop using the sync broker on OS X

mojo/edk/system/node_controller.h

 // Copyright 2016 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 MOJO_EDK_SYSTEM_NODE_CONTROLLER_H_
 #define MOJO_EDK_SYSTEM_NODE_CONTROLLER_H_
 
 #include <queue>
 #include <unordered_map>
 #include <unordered_set>
@@ skipping 235 matching lines @@
   // All other fields below must only be accessed on the I/O thread, i.e., the
   // thread on which core_->io_task_runner() runs tasks.
 
   // Channels to children during handshake.
   NodeMap pending_children_;
 
   // Indicates whether this object should delete itself on IO thread shutdown.
   // Must only be accessed from the IO thread.
   bool destroy_on_io_thread_shutdown_ = false;
 
-#if defined(OS_POSIX)
-  // Broker for sync shared buffer creation (posix-only) in children.
+#if defined(OS_POSIX) && !defined(OS_MACOSX)
+  // Broker for sync shared buffer creation (non-Mac posix-only) in children.
   scoped_ptr<Broker> broker_;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(NodeController);
 };
 
 }  // namespace edk
 }  // namespace mojo
 
 #endif  // MOJO_EDK_SYSTEM_NODE_CONTROLLER_H_