Make QuicTransportClientSession implement QuicCryptoClientStream::ProofHandler.

This way, we can listen to OnProofVerifyDetailsAvailable() in Chrome, and provide more detailed logging for certificate verification events.

PiperOrigin-RevId: 325461898
Change-Id: I5e4dbcc5e058f2bbe8deda79c6d24d985d535ff8
diff --git a/quic/quic_transport/quic_transport_client_session.h b/quic/quic_transport/quic_transport_client_session.h
index 56b29e4..a519d04 100644
--- a/quic/quic_transport/quic_transport_client_session.h
+++ b/quic/quic_transport/quic_transport_client_session.h
@@ -31,7 +31,8 @@
 // A client session for the QuicTransport protocol.
 class QUIC_EXPORT_PRIVATE QuicTransportClientSession
     : public QuicSession,
-      public QuicTransportSessionInterface {
+      public QuicTransportSessionInterface,
+      public QuicCryptoClientStream::ProofHandler {
  public:
   class QUIC_EXPORT_PRIVATE ClientVisitor {
    public:
@@ -111,6 +112,11 @@
 
   using QuicSession::datagram_queue;
 
+  // QuicCryptoClientStream::ProofHandler implementation.
+  void OnProofValid(const QuicCryptoClientConfig::CachedState& cached) override;
+  void OnProofVerifyDetailsAvailable(
+      const ProofVerifyDetails& verify_details) override;
+
  protected:
   class QUIC_EXPORT_PRIVATE ClientIndication : public QuicStream {
    public: