Start using the loss timeout in QuicSentPacketManager and add a mock

net/quic/quic_sent_packet_manager.cc

Index: net/quic/quic_sent_packet_manager.cc
diff --git a/net/quic/quic_sent_packet_manager.cc b/net/quic/quic_sent_packet_manager.cc
index 17cd836b812c12fd2b6463e51830fc9977180053..d7f0a6060b5b1620b8a410893b135b7e516f163b 100644
--- a/net/quic/quic_sent_packet_manager.cc
+++ b/net/quic/quic_sent_packet_manager.cc
@@ -408,6 +408,9 @@ void QuicSentPacketManager::OnRetransmissionTimeout() {
       ++stats_->crypto_retransmit_count;
       RetransmitCryptoPackets();
       return;
+    case LOSS_MODE:
+      InvokeLossDetection(clock_->Now());
+      return;
     case TLP_MODE:
       // If no tail loss probe can be sent, because there are no retransmittable
       // packets, execute a conventional RTO to abandon old packets.
@@ -497,6 +500,9 @@ QuicSentPacketManager::RetransmissionTimeoutMode
   if (pending_crypto_packet_count_ > 0) {
     return HANDSHAKE_MODE;
   }
+  if (loss_algorithm_->GetLossTimeout() != QuicTime::Zero()) {
+    return LOSS_MODE;
+  }
   if (consecutive_tlp_count_ < max_tail_loss_probes_) {
     if (unacked_packets_.HasUnackedRetransmittableFrames()) {
       return TLP_MODE;
@@ -639,6 +645,8 @@ const QuicTime QuicSentPacketManager::GetRetransmissionTime() const {
   switch (GetRetransmissionMode()) {
     case HANDSHAKE_MODE:
       return clock_->ApproximateNow().Add(GetCryptoRetransmissionDelay());
+    case LOSS_MODE:
+      return loss_algorithm_->GetLossTimeout();
     case TLP_MODE: {
       // TODO(ianswett): When CWND is available, it would be preferable to
       // set the timer based on the earliest retransmittable packet.