Fix a QUIC bug where a packet could remain in the UnackedPacketMap

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 759bd7ba2c3328f7c9897121e93eb101709a92f0..65c15ddf7e609511113d46e50d17ed00af36cfda 100644
--- a/net/quic/quic_unacked_packet_map.h
+++ b/net/quic/quic_unacked_packet_map.h
@@ -122,8 +122,10 @@ class NET_EXPORT_PRIVATE QuicUnackedPacketMap {
   // frames, and sets all_transmissions to only include itself.
   void NeuterPacket(QuicPacketSequenceNumber sequence_number);
 
-  // Returns true if the packet has been marked as sent by SetSent.
-  static bool IsSentAndNotPending(const TransmissionInfo& transmission_info);
+  // Returns true if the packet's only purpose is to measure RTT.  It must not
+  // be pending, have retransmittable frames, or be linked to transmissions
+  // with retransmittable frames.
+  static bool IsForRttOnly(const TransmissionInfo& transmission_info);
 
  private:
   void MaybeRemoveRetransmittableFrames(TransmissionInfo* transmission_info);