Read and interpret PRIORITY_UPDATE frame.

gfe-relnote: n/a, change to QUIC v99-only code.  Protected by existing disabled gfe2_reloadable_flag_quic_enable_version_99.
PiperOrigin-RevId: 290869051
Change-Id: Ie5c016bd4254bffad7910d248e483976a249a27d
diff --git a/quic/core/quic_session.cc b/quic/core/quic_session.cc
index 319f3f4..5f3ea29 100644
--- a/quic/core/quic_session.cc
+++ b/quic/core/quic_session.cc
@@ -1644,6 +1644,18 @@
   }
 }
 
+bool QuicSession::MaybeSetStreamPriority(
+    QuicStreamId stream_id,
+    const spdy::SpdyStreamPrecedence& precedence) {
+  auto active_stream = stream_map_.find(stream_id);
+  if (active_stream != stream_map_.end()) {
+    active_stream->second->SetPriority(precedence);
+    return true;
+  }
+
+  return false;
+}
+
 bool QuicSession::IsClosedStream(QuicStreamId id) {
   DCHECK_NE(QuicUtils::GetInvalidStreamId(transport_version()), id);
   if (IsOpenStream(id)) {