gfe-relnote: Let GFE be able to use HTTP2(tree-style) priority write scheduler in QUIC and enable it via a connection option H2PR. Protected by gfe2_reloadable_flag_quic_use_http2_priority_write_scheduler.

PiperOrigin-RevId: 260938733
Change-Id: I6d3f6c325a07b17bdfd8c416add8327b8d54be8a
diff --git a/quic/core/quic_session.h b/quic/core/quic_session.h
index ba5592a..d6f8a60 100644
--- a/quic/core/quic_session.h
+++ b/quic/core/quic_session.h
@@ -434,6 +434,10 @@
     return connection_->transport_version();
   }
 
+  bool use_http2_priority_write_scheduler() const {
+    return use_http2_priority_write_scheduler_;
+  }
+
  protected:
   using StreamMap = QuicSmallMap<QuicStreamId, std::unique_ptr<QuicStream>, 10>;
 
@@ -721,6 +725,10 @@
   // Supported version list used by the crypto handshake only. Please note, this
   // list may be a superset of the connection framer's supported versions.
   ParsedQuicVersionVector supported_versions_;
+
+  // If true, write_blocked_streams_ uses HTTP2 (tree-style) priority write
+  // scheduler.
+  bool use_http2_priority_write_scheduler_;
 };
 
 }  // namespace quic