Mojo: Add NotifyBadMessage API

mojo/edk/system/message_for_transit.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_MESSAGE_FOR_TRANSIT_H_
 #define MOJO_EDK_SYSTEM_MESSAGE_FOR_TRANSIT_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 71 matching lines @@
   }
 
   size_t num_bytes() const {
     size_t header_size = header()->header_size;
     DCHECK_GE(message_->num_payload_bytes(), header_size);
     return message_->num_payload_bytes() - header_size;
   }
 
   size_t num_handles() const { return header()->num_dispatchers; }
 
+  const PortsMessage& ports_message() const { return *message_; }
+
   std::unique_ptr<PortsMessage> TakePortsMessage() {
     return std::move(message_);
   }
 
  private:
   explicit MessageForTransit(std::unique_ptr<PortsMessage> message);
 
   const MessageForTransit::MessageHeader* header() const {
     DCHECK(message_);
     return static_cast<const MessageForTransit::MessageHeader*>(
         message_->payload_bytes());
   }
 
   std::unique_ptr<PortsMessage> message_;
 
   DISALLOW_COPY_AND_ASSIGN(MessageForTransit);
 };
 
 }  // namespace edk
 }  // namespace mojo
 
 #endif  // MOJO_EDK_SYSTEM_MESSAGE_FOR_TRANSIT_H_