Deprecate gfe2_reloadable_flag_quic_donot_pto_stream_data_before_handshake_confirmed.

PiperOrigin-RevId: 499353849

quiche/quic/core/quic_flags_list.h

diff --git a/quiche/quic/core/quic_flags_list.h b/quiche/quic/core/quic_flags_list.h
index 4232a21..0730c8d 100644
--- a/quiche/quic/core/quic_flags_list.h
+++ b/quiche/quic/core/quic_flags_list.h
@@ -49,8 +49,6 @@
 QUIC_FLAG(quic_reloadable_flag_quic_enable_disable_resumption, true)
 // If true, discard INITIAL packet if the key has been dropped.
 QUIC_FLAG(quic_reloadable_flag_quic_discard_initial_packet_with_key_dropped, true)
-// If true, do not PTO new stream data before handshake confirmed.
-QUIC_FLAG(quic_reloadable_flag_quic_donot_pto_stream_data_before_handshake_confirmed, true)
 // If true, do not issue a new connection ID that has been claimed by another connection.
 QUIC_FLAG(quic_reloadable_flag_quic_check_cid_collision_when_issue_new_cid, true)
 // If true, enable server retransmittable on wire PING.

quiche/quic/core/quic_session.cc

diff --git a/quiche/quic/core/quic_session.cc b/quiche/quic/core/quic_session.cc
index 5f132d0..898a869 100644
--- a/quiche/quic/core/quic_session.cc
+++ b/quiche/quic/core/quic_session.cc
@@ -646,9 +646,7 @@
   if (control_frame_manager_.WillingToWrite()) {
     control_frame_manager_.OnCanWrite();
   }
-  if (GetQuicReloadableFlag(
-          quic_donot_pto_stream_data_before_handshake_confirmed) &&
-      version().UsesTls() && GetHandshakeState() != HANDSHAKE_CONFIRMED &&
+  if (version().UsesTls() && GetHandshakeState() != HANDSHAKE_CONFIRMED &&
       connection_->in_probe_time_out()) {
     QUIC_CODE_COUNT(quic_donot_pto_stream_data_before_handshake_confirmed);
     // Do not PTO stream data before handshake gets confirmed.

quiche/quic/core/quic_session_test.cc

diff --git a/quiche/quic/core/quic_session_test.cc b/quiche/quic/core/quic_session_test.cc
index 4118657..1547f18 100644
--- a/quiche/quic/core/quic_session_test.cc
+++ b/quiche/quic/core/quic_session_test.cc
@@ -3158,13 +3158,8 @@
   // Buffered crypto data gets sent.
   EXPECT_CALL(*connection_, SendCryptoData(ENCRYPTION_INITIAL, _, _))
       .WillOnce(Return(350));
-  if (GetQuicReloadableFlag(
-          quic_donot_pto_stream_data_before_handshake_confirmed)) {
-    // Verify stream data is not sent on PTO before handshake confirmed.
-    EXPECT_CALL(*stream, OnCanWrite()).Times(0);
-  } else {
-    EXPECT_CALL(*stream, OnCanWrite());
-  }
+  // Verify stream data is not sent on PTO before handshake confirmed.
+  EXPECT_CALL(*stream, OnCanWrite()).Times(0);
 
   // Fire PTO.
   QuicConnectionPeer::SetInProbeTimeOut(connection_, true);