Add code count for quic_send_goaway_with_connection_close.

Protected by FLAGS_quic_reloadable_flag_quic_send_goaway_with_connection_close.

PiperOrigin-RevId: 340430923
Change-Id: I924085a90c6dd26172d118b619fcd158e57dbbbf

quic/core/http/quic_spdy_session.cc

diff --git a/quic/core/http/quic_spdy_session.cc b/quic/core/http/quic_spdy_session.cc
index eb7228b..0adcdc7 100644
--- a/quic/core/http/quic_spdy_session.cc
+++ b/quic/core/http/quic_spdy_session.cc
@@ -1364,6 +1364,7 @@
 void QuicSpdySession::BeforeConnectionCloseSent() {
   if (GetQuicReloadableFlag(quic_send_goaway_with_connection_close) &&
       VersionUsesHttp3(transport_version()) && IsEncryptionEstablished()) {
+    QUIC_CODE_COUNT(quic_send_goaway_with_connection_close);
     SendHttp3GoAway();
   }
 }