Add CompositeMachMessageServer and its test

util/mach/child_port_server.cc

 // Copyright 2014 The Crashpad Authors. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
@@ skipping 85 matching lines @@
                                              in_trailer,
                                              destroy_complex_request);
       return true;
     }
   }
 
   SetMIGReplyError(out_header, MIG_BAD_ID);
   return false;
 }
 
+std::set<mach_msg_id_t> ChildPortServer::MachMessageServerRequestIDs() {
+  const mach_msg_id_t request_ids[] = {kMachMessageIDChildPortCheckIn};
+  return std::set<mach_msg_id_t>(
+      &request_ids[0], &request_ids[arraysize(request_ids)]);
+}
+
 mach_msg_size_t ChildPortServer::MachMessageServerRequestSize() {
   return sizeof(__RequestUnion__handle_child_port_subsystem);
 }
 
 mach_msg_size_t ChildPortServer::MachMessageServerReplySize() {
   return sizeof(__ReplyUnion__handle_child_port_subsystem);
 }
 
 }  // namespace crashpad