Decouple Blimp transport output from BlimpConnections using MessagePort.

blimp/net/blimp_transport.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_TRANSPORT_H_
 #define BLIMP_NET_BLIMP_TRANSPORT_H_
 
 #include <memory>
 #include <string>
 
 #include "net/base/completion_callback.h"
 
 namespace blimp {
 
 class BlimpConnection;
+class MessagePort;
 
 // An interface which encapsulates the transport-specific code for
 // establishing network connections between the client and engine.
 // Subclasses of BlimpTransport are responsible for defining their own
 // methods for receiving connection arguments.
 class BlimpTransport {
  public:
   virtual ~BlimpTransport() {}
 
   // Initiate or listen for a connection.
   //
-  // |callback| will be invoked with the connection outcome:
-  //   * net::OK if a connection is established successful, the BlimpConnection
-  //     can be taken by calling TakeConnection().
-  //   * net::ERR_IO_PENDING will never be the outcome
-  //   * Other error code indicates no connection was established.
+  // |callback| is passed net::OK if a connection was successfully
+  // established. The connection's MessagePort can then be taken by calling
+  // TakeMessagePort().
+  // All other values indicate a connection error.
   virtual void Connect(const net::CompletionCallback& callback) = 0;
 
-  // Returns the connection object after a successful Connect().
-  virtual std::unique_ptr<BlimpConnection> TakeConnection() = 0;
+  // Returns the MessagePort of a successfully established connection.
+  virtual std::unique_ptr<MessagePort> TakeMessagePort() = 0;
 
-  // Gets transport name, e.g. "TCP", "SSL", "mock", etc.
+  // Gets the transport name, e.g. "TCP", "SSL", "mock", etc.
   virtual const char* GetName() const = 0;
 };
 
 }  // namespace blimp
 
 #endif  // BLIMP_NET_BLIMP_TRANSPORT_H_