Use Chromium BUILD to approximate Blimp protocol version, and check it.

blimp/net/blimp_connection.h

 // Copyright 2015 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 BLIMP_NET_BLIMP_CONNECTION_H_
 #define BLIMP_NET_BLIMP_CONNECTION_H_
 
 #include <memory>
 
 #include "base/macros.h"
@@ skipping 26 matching lines @@
 
   // Sets the processor which will take incoming messages for this connection.
   // Can be set multiple times, but previously set processors are discarded.
   // Caller retains the ownership of |processor|.
   virtual void SetIncomingMessageProcessor(BlimpMessageProcessor* processor);
 
   // Gets a processor for BrowserSession->BlimpConnection message routing.
   virtual BlimpMessageProcessor* GetOutgoingMessageProcessor();
 
  protected:
+  class EndConnectionFilter;
+  friend class EndConnectionFilter;
+
   BlimpConnection();
 
   // ConnectionErrorObserver implementation.
   void OnConnectionError(int error) override;
 
  private:
   std::unique_ptr<PacketReader> reader_;
   std::unique_ptr<BlimpMessagePump> message_pump_;
   std::unique_ptr<PacketWriter> writer_;
   std::unique_ptr<BlimpMessageSender> outgoing_msg_processor_;
   base::ObserverList<ConnectionErrorObserver> error_observers_;
+  std::unique_ptr<EndConnectionFilter> end_connection_filter_;
 
   DISALLOW_COPY_AND_ASSIGN(BlimpConnection);
 };
 
 }  // namespace blimp
 
 #endif  // BLIMP_NET_BLIMP_CONNECTION_H_