Always send queued retransmission packets, because of write blocked socket, once the socket gets un…

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 90cdc3eba63c9a36a4dc6b10416dc65424739e91..d233ad2aa94cfb1582cc4f817f0f15f93537c32d 100644
--- a/net/quic/quic_unacked_packet_map.cc
+++ b/net/quic/quic_unacked_packet_map.cc
@@ -90,10 +90,18 @@ void QuicUnackedPacketMap::TransferRetransmissionInfo(
     QuicPacketNumber new_packet_number,
     TransmissionType transmission_type,
     TransmissionInfo* info) {
-  if (old_packet_number < least_unacked_ ||
-      old_packet_number > largest_sent_packet_) {
-    QUIC_BUG << "Old TransmissionInfo no longer exists for:"
-             << old_packet_number << " least_unacked:" << least_unacked_
+  if (old_packet_number < least_unacked_) {
+    if (!FLAGS_quic_always_write_queued_retransmissions) {
+      QUIC_BUG << "Old TransmissionInfo no longer exists for:"
+               << old_packet_number << " least_unacked:" << least_unacked_;
+    }
+    // This can happen when a retransmission packet is queued because of write
+    // blocked socket, and the original packet gets acked before the
+    // retransmission gets sent.
+    return;
+  }
+  if (old_packet_number > largest_sent_packet_) {
+    QUIC_BUG << "Old TransmissionInfo never existed for :" << old_packet_number
              << " largest_sent:" << largest_sent_packet_;
     return;
   }