Add FLAG_COUNT for flag --gfe2_reloadable_flag_quic_no_write_control_frame_upon_connection_close.

PiperOrigin-RevId: 616181290

quiche/quic/core/quic_session.cc

diff --git a/quiche/quic/core/quic_session.cc b/quiche/quic/core/quic_session.cc
index ee5c23f..53264f1 100644
--- a/quiche/quic/core/quic_session.cc
+++ b/quiche/quic/core/quic_session.cc
@@ -679,6 +679,10 @@
              quic_no_write_control_frame_upon_connection_close) &&
          !connection_->connected()) ||
         crypto_stream->HasBufferedCryptoFrames()) {
+      if (!connection_->connected()) {
+        QUIC_RELOADABLE_FLAG_COUNT(
+            quic_no_write_control_frame_upon_connection_close);
+      }
       // Cannot finish writing buffered crypto frames, connection is either
       // write blocked or closed.
       return;