Add HttpDecoder::OnPriorityFrameStart() so that QuicSpdyStream knows the size
of the priority frame and can consume correct amount of bytes.

gfe-relnote: v99 only, not in prod.
PiperOrigin-RevId: 254279623
Change-Id: Ic24fd04b055033c0735a224e76a949714b3ef268
diff --git a/quic/core/http/quic_spdy_stream.cc b/quic/core/http/quic_spdy_stream.cc
index aa20771..02601ba 100644
--- a/quic/core/http/quic_spdy_stream.cc
+++ b/quic/core/http/quic_spdy_stream.cc
@@ -8,6 +8,7 @@
 #include <string>
 #include <utility>
 
+#include "net/third_party/quiche/src/quic/core/http/http_decoder.h"
 #include "net/third_party/quiche/src/quic/core/http/quic_spdy_session.h"
 #include "net/third_party/quiche/src/quic/core/http/spdy_utils.h"
 #include "net/third_party/quiche/src/quic/core/qpack/qpack_decoded_headers_accumulator.h"
@@ -45,6 +46,11 @@
         ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET);
   }
 
+  bool OnPriorityFrameStart(Http3FrameLengths /*frame_lengths*/) override {
+    CloseConnectionOnWrongFrame("Priority");
+    return false;
+  }
+
   bool OnPriorityFrame(const PriorityFrame& /*frame*/) override {
     CloseConnectionOnWrongFrame("Priority");
     return false;