Handle closing pending streams.

Make QuicSession handle if a pending stream is closed before it gets converted
into the appropriate incoming stream subclass.

gfe-relnote: n/a, no functional change outside QUIC v99-only code.  Protected by existing disabled gfe2_reloadable_flag_quic_enable_version_99.
PiperOrigin-RevId: 262183753
Change-Id: I4147320860b867df0d80ba8fd55106bf779b15b3
diff --git a/quic/test_tools/quic_session_peer.h b/quic/test_tools/quic_session_peer.h
index f027eb5..decc4b9 100644
--- a/quic/test_tools/quic_session_peer.h
+++ b/quic/test_tools/quic_session_peer.h
@@ -86,6 +86,8 @@
                                  QuicRstStreamErrorCode error,
                                  QuicStreamOffset bytes_written,
                                  bool close_write_side_only);
+  static PendingStream* GetPendingStream(QuicSession* session,
+                                         QuicStreamId stream_id);
 };
 
 }  // namespace test