Remove spdy_session->promised_stream_id() and spdy_session->OnHeadersList() calls from QuicSpdyStream::OnHeadersDecoded().

This is vestigial from the never-finished HTTP/3 push implementation.
QuicSpdyStream::OnHeadersDecoded() is only called in HTTP/3, but
QuicSpdySession::promised_stream_id() can only possibly be different from the
invalid stream ID in gQUIC.
PiperOrigin-RevId: 572696516

quiche/quic/core/http/quic_spdy_session.cc

diff --git a/quiche/quic/core/http/quic_spdy_session.cc b/quiche/quic/core/http/quic_spdy_session.cc
index 69c6382..d2376e6 100644
--- a/quiche/quic/core/http/quic_spdy_session.cc
+++ b/quiche/quic/core/http/quic_spdy_session.cc
@@ -1420,11 +1420,8 @@
 void QuicSpdySession::OnHeaderList(const QuicHeaderList& header_list) {
   QUIC_DVLOG(1) << ENDPOINT << "Received header list for stream " << stream_id_
                 << ": " << header_list.DebugString();
-  // This code path is only executed for push promise in IETF QUIC.
-  if (VersionUsesHttp3(transport_version())) {
-    QUICHE_DCHECK(promised_stream_id_ !=
-                  QuicUtils::GetInvalidStreamId(transport_version()));
-  }
+  QUICHE_DCHECK(!VersionUsesHttp3(transport_version()));
+
   // Ignore push request headers.
   if (promised_stream_id_ ==
       QuicUtils::GetInvalidStreamId(transport_version())) {

quiche/quic/core/http/quic_spdy_stream.cc

diff --git a/quiche/quic/core/http/quic_spdy_stream.cc b/quiche/quic/core/http/quic_spdy_stream.cc
index 1edcd4a..aeb8547 100644
--- a/quiche/quic/core/http/quic_spdy_stream.cc
+++ b/quiche/quic/core/http/quic_spdy_stream.cc
@@ -554,19 +554,13 @@
       /* is_sent = */ false, headers.compressed_header_bytes(),
       headers.uncompressed_header_bytes());
 
-  const QuicStreamId promised_stream_id = spdy_session()->promised_stream_id();
   Http3DebugVisitor* const debug_visitor = spdy_session()->debug_visitor();
-  if (promised_stream_id ==
-      QuicUtils::GetInvalidStreamId(transport_version())) {
-    if (debug_visitor) {
-      debug_visitor->OnHeadersDecoded(id(), headers);
-    }
-
-    OnStreamHeaderList(/* fin = */ false, headers_payload_length_, headers);
-  } else {
-    spdy_session_->OnHeaderList(headers);
+  if (debug_visitor) {
+    debug_visitor->OnHeadersDecoded(id(), headers);
   }
 
+  OnStreamHeaderList(/* fin = */ false, headers_payload_length_, headers);
+
   if (blocked_on_decoding_headers_) {
     blocked_on_decoding_headers_ = false;
     // Continue decoding HTTP/3 frames.