Do not delete QuicConfig in YperfSession.

Tested with blaze test //vr/c9/playability/yperf:yperf_channel_v2_test --config=tsan --test_arg='--gfe2_invert_all_feature_flags_for_test=true'

PiperOrigin-RevId: 867828783

quiche/quic/core/quic_session.cc

diff --git a/quiche/quic/core/quic_session.cc b/quiche/quic/core/quic_session.cc
index 483e800..bfb3e54 100644
--- a/quiche/quic/core/quic_session.cc
+++ b/quiche/quic/core/quic_session.cc
@@ -39,6 +39,7 @@
 #include "quiche/quic/platform/api/quic_flags.h"
 #include "quiche/quic/platform/api/quic_logging.h"
 #include "quiche/quic/platform/api/quic_server_stats.h"
+#include "quiche/common/platform/api/quiche_flag_utils.h"
 #include "quiche/common/platform/api/quiche_logging.h"
 #include "quiche/common/quiche_callbacks.h"
 #include "quiche/common/quiche_text_utils.h"
@@ -150,6 +151,7 @@
   received_max_bidirectional_streams_ =
       config_->ReceivedMaxBidirectionalStreams();
   idle_network_timeout_ = config_->IdleNetworkTimeout();
+  QUICHE_RELOADABLE_FLAG_COUNT(quic_delete_config);
   config_.reset();
 }
 

quiche/quic/core/quic_session.h

diff --git a/quiche/quic/core/quic_session.h b/quiche/quic/core/quic_session.h
index 850d741..f205c64 100644
--- a/quiche/quic/core/quic_session.h
+++ b/quiche/quic/core/quic_session.h
@@ -240,11 +240,15 @@
       return config_->IdleNetworkTimeout();
     }
 
+    void set_delete_config(bool delete_config) {
+      delete_config_ = delete_config;
+    }
+
    private:
     std::unique_ptr<QuicConfig> config_;
     // TODO(b/461482627): Delete this when retiring the flag.
     bool config_deleted_ = false;
-    const bool delete_config_ = GetQuicReloadableFlag(quic_delete_config);
+    bool delete_config_ = GetQuicReloadableFlag(quic_delete_config);
 
     bool has_received_initial_stream_flow_control_window_bytes_ = false;
     bool has_received_initial_max_stream_data_bytes_unidirectional_ = false;
@@ -1061,6 +1065,10 @@
 
   bool enforce_immediate_goaway() const { return enforce_immediate_goaway_; }
 
+  void set_delete_config(bool delete_config) {
+    saved_config_.set_delete_config(delete_config);
+  }
+
  private:
   friend class test::QuicSessionPeer;