Add a test requested by rch@ in cr/59053386 to replicate a potential

net/quic/quic_sent_packet_manager_test.cc

Index: net/quic/quic_sent_packet_manager_test.cc
diff --git a/net/quic/quic_sent_packet_manager_test.cc b/net/quic/quic_sent_packet_manager_test.cc
index 77875d7c2de03a839e79b40ca06d2c4e0f249920..b0e861d921a8a465a3fec2fe9ecffff1adf15033 100644
--- a/net/quic/quic_sent_packet_manager_test.cc
+++ b/net/quic/quic_sent_packet_manager_test.cc
@@ -1038,6 +1038,23 @@ TEST_F(QuicSentPacketManagerTest, CryptoHandshakeTimeoutUnsentDataPacket) {
   EXPECT_TRUE(QuicSentPacketManagerPeer::HasUnackedCryptoPackets(&manager_));
 }
 
+TEST_F(QuicSentPacketManagerTest, TailLossProbeTimeoutUnsentDataPacket) {
+  QuicSentPacketManagerPeer::SetMaxTailLossProbes(&manager_, 2);
+  // Serialize two data packets and send the latter.
+  SerializedPacket packet(CreateDataPacket(1));
+  manager_.OnSerializedPacket(packet);
+  SendDataPacket(2);
+  EXPECT_FALSE(QuicSentPacketManagerPeer::HasUnackedCryptoPackets(&manager_));
+  EXPECT_TRUE(QuicSentPacketManagerPeer::HasPendingPackets(&manager_));
+
+  // Retransmit 1 unacked packets, but not the first serialized packet.
+  manager_.OnRetransmissionTimeout();
+  RetransmitNextPacket(3);
+  EXPECT_FALSE(manager_.HasPendingRetransmissions());
+  EXPECT_FALSE(QuicSentPacketManagerPeer::HasUnackedCryptoPackets(&manager_));
+  EXPECT_TRUE(QuicSentPacketManagerPeer::HasPendingPackets(&manager_));
+}
+
 TEST_F(QuicSentPacketManagerTest, RetransmissionTimeout) {
   // Send 100 packets and then ensure all are abandoned when the RTO fires.
   const size_t kNumSentPackets = 100;