Remove ack bundling mode.

gfe-relnote: Deprecate gfe2_reloadable_flag_quic_deprecate_ack_bundling_mode.
PiperOrigin-RevId: 253856112
Change-Id: Iaa62b97be5904743c56c5b48b230446a9c4bd870
diff --git a/quic/core/qpack/qpack_send_stream.cc b/quic/core/qpack/qpack_send_stream.cc
index 73d62f3..620ab2b 100644
--- a/quic/core/qpack/qpack_send_stream.cc
+++ b/quic/core/qpack/qpack_send_stream.cc
@@ -24,8 +24,7 @@
 }
 
 void QpackSendStream::WriteStreamData(QuicStringPiece data) {
-  QuicConnection::ScopedPacketFlusher flusher(
-      session()->connection(), QuicConnection::SEND_ACK_IF_PENDING);
+  QuicConnection::ScopedPacketFlusher flusher(session()->connection());
   if (!stream_type_sent_) {
     char type[sizeof(stream_type_)];
     QuicDataWriter writer(QUIC_ARRAYSIZE(type), type);