Update from https://crrev.com/316786

net/quic/quic_ack_notifier.h

 // Copyright 2013 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 NET_QUIC_QUIC_ACK_NOTIFIER_H_
 #define NET_QUIC_QUIC_ACK_NOTIFIER_H_
 
 #include "base/memory/ref_counted.h"
 #include "net/quic/quic_protocol.h"
 
@@ skipping 22 matching lines @@
     friend class base::RefCounted<DelegateInterface>;
 
     // Delegates are ref counted.
     virtual ~DelegateInterface();
   };
 
   // QuicAckNotifier is expected to keep its own reference to the delegate.
   explicit QuicAckNotifier(DelegateInterface* delegate);
   virtual ~QuicAckNotifier();
 
-  // Register a sequence number that this AckNotifier should be interested in.
-  void AddSequenceNumber(const QuicPacketSequenceNumber& sequence_number,
-                         int packet_payload_size);
+  // Register a serialized packet the notifier should track.
+  void OnSerializedPacket();
 
-  // Called by the QuicConnection on receipt of new ACK frame, with the sequence
-  // number referenced by the ACK frame.
-  // Deletes the matching sequence number from the stored set of sequence
-  // numbers. If this set is now empty, call the stored delegate's
-  // OnAckNotification method.
+  // Called on receipt of new ACK frame for an unacked packet.
+  // Decrements the number of unacked packets and if there are none left, calls
+  // the stored delegate's OnAckNotification method.
   //
-  // Returns true if the provided sequence_number caused the delegate to be
-  // called, false otherwise.
-  bool OnAck(QuicPacketSequenceNumber sequence_number,
-             QuicTime::Delta delta_largest_observed);
+  // Returns true if the delegate was called, false otherwise.
+  bool OnAck(QuicTime::Delta delta_largest_observed);
 
-  bool IsEmpty() { return unacked_packets_ == 0; }
+  // Called when we've given up waiting for a sequence number, typically when
+  // the connection is torn down.
+  // Returns true if there are no more unacked packets being tracked.
+  bool OnPacketAbandoned();
+
+  bool HasUnackedPackets() const { return unacked_packets_ > 0; }
 
   // If a packet is retransmitted by the connection, it will be sent with a
   // different sequence number.
   void OnPacketRetransmitted(int packet_payload_size);
 
  private:
   // The delegate's OnAckNotification() method will be called once we have been
   // notified of ACKs for all the sequence numbers we are tracking.
   // This is not owned by OnAckNotifier and must outlive it.
   scoped_refptr<DelegateInterface> delegate_;
 
   // The number of unacked packets being tracked.
   int unacked_packets_;
 
   // Number of packets that had to be retransmitted.
   int retransmitted_packet_count_;
   // Number of bytes that had to be retransmitted.
   int retransmitted_byte_count_;
 
   DISALLOW_COPY_AND_ASSIGN(QuicAckNotifier);
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_QUIC_ACK_NOTIFIER_H_