Minor cleanup of QuicUnackedPacketMap to simplify the implementation of

net/quic/quic_unacked_packet_map.h

Index: net/quic/quic_unacked_packet_map.h
diff --git a/net/quic/quic_unacked_packet_map.h b/net/quic/quic_unacked_packet_map.h
index 65c15ddf7e609511113d46e50d17ed00af36cfda..12a96a28766713ccbfb444e917c5603167275b12 100644
--- a/net/quic/quic_unacked_packet_map.h
+++ b/net/quic/quic_unacked_packet_map.h
@@ -52,9 +52,6 @@ class NET_EXPORT_PRIVATE QuicUnackedPacketMap {
   // frames.
   bool HasUnackedRetransmittableFrames() const;
 
-  // Returns the number of unacked packets which have retransmittable frames.
-  size_t GetNumRetransmittablePackets() const;
-
   // Returns the largest sequence number that has been sent.
   QuicPacketSequenceNumber largest_sent_packet() const {
     return largest_sent_packet_;