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

net/quic/quic_unacked_packet_map.cc

Index: net/quic/quic_unacked_packet_map.cc
diff --git a/net/quic/quic_unacked_packet_map.cc b/net/quic/quic_unacked_packet_map.cc
index a21d4a5c541bdc7494a947fcfb176cec6bdb29dd..c6f09c682cbe86f88c8c907bbb73721eb0b77098 100644
--- a/net/quic/quic_unacked_packet_map.cc
+++ b/net/quic/quic_unacked_packet_map.cc
@@ -166,11 +166,11 @@ void QuicUnackedPacketMap::MaybeRemoveRetransmittableFrames(
 }
 
 // static
-bool QuicUnackedPacketMap::IsSentAndNotPending(
+bool QuicUnackedPacketMap::IsForRttOnly(
     const TransmissionInfo& transmission_info) {
   return !transmission_info.pending &&
-      transmission_info.sent_time != QuicTime::Zero() &&
-      transmission_info.bytes_sent == 0;
+      transmission_info.retransmittable_frames == NULL &&
+      transmission_info.all_transmissions->size() == 1;
 }
 
 bool QuicUnackedPacketMap::IsUnacked(