Introduce Control streams for HTTP/3.

gfe-relnote: n/a --unused code.
PiperOrigin-RevId: 242161401
Change-Id: I29928112a479348ef66636b442ea6065bd832194
diff --git a/quic/test_tools/quic_spdy_session_peer.h b/quic/test_tools/quic_spdy_session_peer.h
index 58a864d..83e8b0c 100644
--- a/quic/test_tools/quic_spdy_session_peer.h
+++ b/quic/test_tools/quic_spdy_session_peer.h
@@ -41,6 +41,9 @@
       bool fin,
       spdy::SpdyPriority priority,
       QuicReferenceCountedPointer<QuicAckListenerInterface> ack_listener);
+  // |session| can't be nullptr.
+  static QuicStreamId GetNextOutgoingUnidirectionalStreamId(
+      QuicSpdySession* session);
 };
 
 }  // namespace test