Add flag count for quic_stop_sending_uses_ietf_error_code.

I forgot to add it in cl/331000553.

PiperOrigin-RevId: 331165541
Change-Id: I5e04cfa8d8787d2aea468859ae66c62861604670

quic/core/frames/quic_stop_sending_frame.cc

diff --git a/quic/core/frames/quic_stop_sending_frame.cc b/quic/core/frames/quic_stop_sending_frame.cc
index 0a8d546..7623f0d 100644
--- a/quic/core/frames/quic_stop_sending_frame.cc
+++ b/quic/core/frames/quic_stop_sending_frame.cc
@@ -15,7 +15,11 @@
       ietf_error_code(
           GetQuicReloadableFlag(quic_stop_sending_uses_ietf_error_code)
               ? RstStreamErrorCodeToIetfResetStreamErrorCode(error_code)
-              : error_code) {}
+              : error_code) {
+  if (GetQuicReloadableFlag(quic_stop_sending_uses_ietf_error_code)) {
+    QUIC_RELOADABLE_FLAG_COUNT_N(quic_stop_sending_uses_ietf_error_code, 1, 2);
+  }
+}
 
 std::ostream& operator<<(std::ostream& os, const QuicStopSendingFrame& frame) {
   os << "{ control_frame_id: " << frame.control_frame_id

quic/core/quic_framer.cc

diff --git a/quic/core/quic_framer.cc b/quic/core/quic_framer.cc
index 07ea943..b3a5fe1 100644
--- a/quic/core/quic_framer.cc
+++ b/quic/core/quic_framer.cc
@@ -5913,6 +5913,7 @@
   }
 
   if (GetQuicReloadableFlag(quic_stop_sending_uses_ietf_error_code)) {
+    QUIC_RELOADABLE_FLAG_COUNT_N(quic_stop_sending_uses_ietf_error_code, 2, 2);
     stop_sending_frame->error_code =
         IetfResetStreamErrorCodeToRstStreamErrorCode(
             stop_sending_frame->ietf_error_code);