Refactoring: Create per-connection packet writers in QuicDispatcher.

net/quic/quic_connection.h

 // Copyright (c) 2012 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.
 //
 // The entity that handles framing writes for a Quic client or server.
 // Each QuicSession will have a connection associated with it.
 //
 // On the server side, the Dispatcher handles the raw reads, and hands off
 // packets via ProcessUdpPacket for framing and processing.
 //
@@ skipping 218 matching lines @@
     QUEUED,
     CONNECTION_CLOSE
   };
 
   enum AckBundling {
     NO_ACK = 0,
     SEND_ACK = 1,
     BUNDLE_PENDING_ACK = 2,
   };
 
-  // Constructs a new QuicConnection for |connection_id| and |address|.
-  // |helper| must outlive this connection, and if |owns_writer| is false, so
-  // must |writer|.
+  class PacketWriterFactory {
+   public:
+    virtual ~PacketWriterFactory() {}
+
+    virtual QuicPacketWriter* Create(QuicConnection* connection) const = 0;
+  };
+
+  // Constructs a new QuicConnection for |connection_id| and |address|. Invokes
+  // writer_factory->Create() to get a writer; |owns_writer| specifies whether
+  // the connection takes ownership of the returned writer. |helper| must
+  // outlive this connection.
   QuicConnection(QuicConnectionId connection_id,
                  IPEndPoint address,
                  QuicConnectionHelperInterface* helper,
-                 QuicPacketWriter* writer,
+                 const PacketWriterFactory& writer_factory,
                  bool owns_writer,
                  bool is_server,
                  const QuicVersionVector& supported_versions);
   virtual ~QuicConnection();
 
   // Sets connection parameters from the supplied |config|.
   void SetFromConfig(const QuicConfig& config);
 
   // Send the data in |data| to the peer in as few packets as possible.
   // Returns a pair with the number of bytes consumed from data, and a boolean
@@ skipping 540 matching lines @@
   // If non-empty this contains the set of versions received in a
   // version negotiation packet.
   QuicVersionVector server_supported_versions_;
 
   DISALLOW_COPY_AND_ASSIGN(QuicConnection);
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_QUIC_CONNECTION_H_