Fix a flaky EndToEndTest where packet loss is possible with a large

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 0dbd186870eed51f5adc61c2ae5f09c0466a7425..121a7a5ae423f12c5939c7c80131248c015c9cea 100644
--- a/net/quic/quic_sent_packet_manager.cc
+++ b/net/quic/quic_sent_packet_manager.cc
@@ -602,6 +602,7 @@ void QuicSentPacketManager::InvokeLossDetection(QuicTime time) {
     // until it's known whether the FEC packet arrived.
     ++stats_->packets_lost;
     packets_lost_[sequence_number] = transmission_info;
+    DVLOG(1) << ENDPOINT << "Lost packet " << sequence_number;
 
     if (transmission_info.retransmittable_frames != NULL) {
       MarkForRetransmission(sequence_number, LOSS_RETRANSMISSION);