gfe-relnote: Add some bbr startup stats into QuicConnectionStats. Stats only. Not protected.

PiperOrigin-RevId: 241339065
Change-Id: Idef0c196eb0ab6bbe202a33d79e65a88a43678fd

quic/core/quic_connection_stats.cc

diff --git a/quic/core/quic_connection_stats.cc b/quic/core/quic_connection_stats.cc
index 5dea2ea..4d5c578 100644
--- a/quic/core/quic_connection_stats.cc
+++ b/quic/core/quic_connection_stats.cc
@@ -20,9 +20,14 @@
       bytes_spuriously_retransmitted(0),
       packets_spuriously_retransmitted(0),
       packets_lost(0),
+      slowstart_count(0),
+      slowstart_num_rtts(0),
       slowstart_packets_sent(0),
+      slowstart_bytes_sent(0),
       slowstart_packets_lost(0),
       slowstart_bytes_lost(0),
+      slowstart_duration(QuicTime::Delta::Zero()),
+      slowstart_start_time(QuicTime::Zero()),
       packets_dropped(0),
       crypto_retransmit_count(0),
       loss_timeout_count(0),