Refactor QuicConnection's async write behavior to record a packet as

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 692 matching lines @@
 
   // When the version negotiation packet could not be sent because the socket
   // was not writable, this is set to true.
   bool pending_version_negotiation_packet_;
 
   // When packets could not be sent because the socket was not writable,
   // they are added to this list.  All corresponding frames are in
   // unacked_packets_ if they are to be retransmitted.
   QueuedPacketList queued_packets_;
 
-  // Contains information about the current write in progress, if any.
-  scoped_ptr<QueuedPacket> pending_write_;
-
   // Contains the connection close packet if the connection has been closed.
   scoped_ptr<QuicEncryptedPacket> connection_close_packet_;
 
   FecGroupMap group_map_;
 
   QuicReceivedPacketManager received_packet_manager_;
   QuicSentEntropyManager sent_entropy_manager_;
 
   // Indicates whether an ack should be sent the next time we try to write.
   bool ack_queued_;
@@ skipping 74 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_