Deprecate quic_always_has_unacked_packets_on_timeout

net/quic/quic_connection.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/quic/quic_connection.h"
 
 #include <string.h>
 #include <sys/types.h>
 
 #include <algorithm>
@@ skipping 1823 matching lines @@
   ack_queued_ = false;
   stop_waiting_count_ = 0;
   num_retransmittable_packets_received_since_last_ack_sent_ = 0;
   last_ack_had_missing_packets_ = received_packet_manager_.HasMissingPackets();
   num_packets_received_since_last_ack_sent_ = 0;
 
   packet_generator_.SetShouldSendAck(true);
 }
 
 void QuicConnection::OnRetransmissionTimeout() {
-  if (FLAGS_quic_always_has_unacked_packets_on_timeout) {
-    DCHECK(sent_packet_manager_.HasUnackedPackets());
-  } else {
-    if (!sent_packet_manager_.HasUnackedPackets()) {
-      return;
-    }
-  }
+  DCHECK(sent_packet_manager_.HasUnackedPackets());
 
   if (close_connection_after_five_rtos_ &&
       sent_packet_manager_.consecutive_rto_count() >= 4) {
     // Close on the 5th consecutive RTO, so after 4 previous RTOs have occurred.
     CloseConnection(QUIC_TOO_MANY_RTOS, "5 consecutive retransmission timeouts",
                     ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET);
     return;
   }
 
   // Cancel the send alarm to ensure TimeUntilSend is re-evaluated.
@@ skipping 573 matching lines @@
 }
 
 StringPiece QuicConnection::GetCurrentPacket() {
   if (current_packet_data_ == nullptr) {
     return StringPiece();
   }
   return StringPiece(current_packet_data_, last_size_);
 }
 
 }  // namespace net