Further cleanup to QuicAckNotifier and QuicAckNotifierManager.

net/quic/quic_ack_notifier.h

Index: net/quic/quic_ack_notifier.h
diff --git a/net/quic/quic_ack_notifier.h b/net/quic/quic_ack_notifier.h
index b9b1cc67a5e06a73c13a68efbb01e3f2e4a19c9a..602d86fefb8024184d4e3436ade27cd89c53ddb4 100644
--- a/net/quic/quic_ack_notifier.h
+++ b/net/quic/quic_ack_notifier.h
@@ -43,16 +43,12 @@ class NET_EXPORT_PRIVATE QuicAckNotifier {
   // 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);
 
   // Called when we've given up waiting for a sequence number, typically when
   // the connection is torn down.