Revert of [mojo-edk] Simplify multiprocess pipe bootstrap

mojo/edk/system/ports/message.cc

 // 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.
 
 #include <stdlib.h>
 
 #include <limits>
 
 #include "base/logging.h"
 #include "mojo/edk/system/ports/event.h"
@@ skipping 19 matching lines @@
     case EventType::kObserveProxy:
       *num_header_bytes = sizeof(EventHeader) + sizeof(ObserveProxyEventData);
       break;
     case EventType::kObserveProxyAck:
       *num_header_bytes =
           sizeof(EventHeader) + sizeof(ObserveProxyAckEventData);
       break;
     case EventType::kObserveClosure:
       *num_header_bytes = sizeof(EventHeader) + sizeof(ObserveClosureEventData);
       break;
-    case EventType::kMergePort:
-      *num_header_bytes = sizeof(EventHeader) + sizeof(MergePortEventData);
-      break;
     default:
       CHECK(false) << "Bad event type";
       return;
   }
 
   if (header->type == EventType::kUser) {
     const UserEventData* event_data =
         reinterpret_cast<const UserEventData*>(
             reinterpret_cast<const char*>(header + 1));
     *num_header_bytes = sizeof(EventHeader) +
@@ skipping 28 matching lines @@
   start_ = static_cast<char*>(start);
   memset(start_, 0, num_header_bytes_);
   GetMutableEventHeader(this)->type = EventType::kUser;
   GetMutableEventData<UserEventData>(this)->num_ports =
       static_cast<uint32_t>(num_ports_);
 }
 
 }  // namespace ports
 }  // namespace edk
 }  // namespace mojo