Fix a bug protected by gfe2_reloadable_flag_quic_respect_send_alarm where acks would not be sent im…

net/quic/quic_connection.cc

Index: net/quic/quic_connection.cc
diff --git a/net/quic/quic_connection.cc b/net/quic/quic_connection.cc
index da8305f42bd488d7e8f9c71e88418ec6a736bcbf..4a1305768dbdec37654fa7204e99bf77fdd33f3f 100644
--- a/net/quic/quic_connection.cc
+++ b/net/quic/quic_connection.cc
@@ -710,7 +710,7 @@ bool QuicConnection::OnAckFrame(const QuicAckFrame& incoming_ack) {
     return false;
   }
 
-  if (FLAGS_quic_respect_send_alarm && send_alarm_->IsSet()) {
+  if (FLAGS_quic_respect_send_alarm2 && send_alarm_->IsSet()) {
     send_alarm_->Cancel();
   }
   ProcessAckFrame(incoming_ack);
@@ -1511,9 +1511,17 @@ bool QuicConnection::CanWrite(HasRetransmittableData retransmittable) {
     return false;
   }
 
-  // If the send alarm is set, wait for it to fire.
-  if (FLAGS_quic_respect_send_alarm && send_alarm_->IsSet()) {
-    return false;
+  if (FLAGS_quic_respect_send_alarm2) {
+    // Allow acks to be sent immediately.
+    // TODO(ianswett): Remove retransmittable from
+    // SendAlgorithmInterface::TimeUntilSend.
+    if (retransmittable == NO_RETRANSMITTABLE_DATA) {
+      return true;
+    }
+    // If the send alarm is set, wait for it to fire.
+    if (send_alarm_->IsSet()) {
+      return false;
+    }
   }
 
   QuicTime now = clock_->Now();
@@ -1531,7 +1539,7 @@ bool QuicConnection::CanWrite(HasRetransmittableData retransmittable) {
              << "ms";
     return false;
   }
-  if (!FLAGS_quic_respect_send_alarm) {
+  if (!FLAGS_quic_respect_send_alarm2) {
     send_alarm_->Cancel();
   }
   return true;
@@ -2266,7 +2274,8 @@ QuicConnection::ScopedPacketBundler::ScopedPacketBundler(
       connection_->ack_alarm_->IsSet() || connection_->stop_waiting_count_ > 1;
   if (send_ack == SEND_ACK || (send_ack == BUNDLE_PENDING_ACK && ack_pending)) {
     DVLOG(1) << "Bundling ack with outgoing packet.";
-    DCHECK(send_ack == SEND_ACK || connection_->ack_frame_updated());
+    DCHECK(send_ack == SEND_ACK || connection_->ack_frame_updated() ||
+           connection_->stop_waiting_count_ > 1);
     connection_->SendAck();
   }
 }