Keep an instance of QuicAckFrame in QuicConnection in order to reduce

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 352 matching lines @@
   bool OnGoAwayFrame(const QuicGoAwayFrame& frame) override;
   bool OnWindowUpdateFrame(const QuicWindowUpdateFrame& frame) override;
   bool OnBlockedFrame(const QuicBlockedFrame& frame) override;
   void OnFecData(const QuicFecData& fec) override;
   void OnPacketComplete() override;
 
   // QuicPacketGenerator::DelegateInterface
   bool ShouldGeneratePacket(TransmissionType transmission_type,
                             HasRetransmittableData retransmittable,
                             IsHandshake handshake) override;
-  QuicAckFrame* CreateAckFrame() override;
-  QuicStopWaitingFrame* CreateStopWaitingFrame() override;
+  void PopulateAckFrame(QuicAckFrame* ack) override;
+  void PopulateStopWaitingFrame(QuicStopWaitingFrame* stop_waiting) override;
   void OnSerializedPacket(const SerializedPacket& packet) override;
 
   // QuicSentPacketManager::NetworkChangeVisitor
   void OnCongestionWindowChange() override;
   void OnRttChange() override;
 
   // Called by the crypto stream when the handshake completes. In the server's
   // case this is when the SHLO has been ACKed. Clients call this on receipt of
   // the SHLO.
   void OnHandshakeComplete();
@@ skipping 237 matching lines @@
   void MaybeProcessUndecryptablePackets();
 
   // If a packet can be revived from the current FEC group, then
   // revive and process the packet.
   void MaybeProcessRevivedPacket();
 
   void ProcessAckFrame(const QuicAckFrame& incoming_ack);
 
   void ProcessStopWaitingFrame(const QuicStopWaitingFrame& stop_waiting);
 
-  // Update |stop_waiting| for an outgoing ack.
-  void UpdateStopWaiting(QuicStopWaitingFrame* stop_waiting);
-
   // Queues an ack or sets the ack alarm when an incoming packet arrives that
   // should be acked.
   void MaybeQueueAck();
 
   // Checks if the last packet should instigate an ack.
   bool ShouldLastPacketInstigateAck() const;
 
   // Checks if the peer is waiting for packets that have been given up on, and
   // therefore an ack frame should be sent with a larger least_unacked.
   void UpdateStopWaitingCount();
@@ skipping 194 matching lines @@
 
   // True if this is a secure QUIC connection.
   bool is_secure_;
 
   DISALLOW_COPY_AND_ASSIGN(QuicConnection);
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_QUIC_CONNECTION_H_