Add mutable_session_cache() to QuicCryptoClientConfig.

PiperOrigin-RevId: 411180182

quic/core/crypto/quic_crypto_client_config.h

diff --git a/quic/core/crypto/quic_crypto_client_config.h b/quic/core/crypto/quic_crypto_client_config.h
index 9d183e9..694e068 100644
--- a/quic/core/crypto/quic_crypto_client_config.h
+++ b/quic/core/crypto/quic_crypto_client_config.h
@@ -394,6 +394,8 @@
   bool pad_full_hello() const { return pad_full_hello_; }
   void set_pad_full_hello(bool new_value) { pad_full_hello_ = new_value; }
 
+  SessionCache* mutable_session_cache() { return session_cache_.get(); }
+
  private:
   // Sets the members to reasonable, default values.
   void SetDefaults();