Suppress erronous TSAN errors in new EDK.

mojo/edk/system/message_in_transit.cc

 // Copyright 2013 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 "mojo/edk/system/message_in_transit.h"
 
 #include <stddef.h>
 #include <stdint.h>
 #include <string.h>
 #include <ostream>
@@ skipping 148 matching lines @@
   // Update the sizes in the message header.
   UpdateTotalSize();
 }
 
 void MessageInTransit::ConstructorHelper(Type type,
                                          uint32_t num_bytes) {
   DCHECK_LE(num_bytes, GetConfiguration().max_message_num_bytes);
 
   // |total_size| is updated below, from the other values.
   header()->type = type;
+  header()->unusedforalignment = 0;
   header()->num_bytes = num_bytes;
   header()->unused = 0;
   header()->route_id = 0;
   // Note: If dispatchers are subsequently attached, then |total_size| will have
   // to be adjusted.
   UpdateTotalSize();
 }
 
 void MessageInTransit::UpdateTotalSize() {
   DCHECK_EQ(main_buffer_size_ % kMessageAlignment, 0u);
   header()->total_size = static_cast<uint32_t>(main_buffer_size_);
   if (transport_data_) {
     header()->total_size +=
         static_cast<uint32_t>(transport_data_->buffer_size());
   }
 }
 
 }  // namespace edk
 }  // namespace mojo