Deprecate gfe2_reloadable_flag_quic_donot_pto_half_rtt_data.

PiperOrigin-RevId: 387173993
diff --git a/quic/core/quic_connection.cc b/quic/core/quic_connection.cc
index 634af51..a45f7db 100644
--- a/quic/core/quic_connection.cc
+++ b/quic/core/quic_connection.cc
@@ -2590,15 +2590,12 @@
   }
   if (perspective_ == Perspective::IS_SERVER &&
       version().CanSendCoalescedPackets() && !IsHandshakeConfirmed()) {
-    if (GetQuicReloadableFlag(quic_donot_pto_half_rtt_data)) {
-      QUIC_RELOADABLE_FLAG_COUNT(quic_donot_pto_half_rtt_data);
-      if (in_on_retransmission_time_out_ &&
-          coalesced_packet_.NumberOfPackets() == 0u) {
-        // PTO fires while handshake is not confirmed. Do not preempt handshake
-        // data with stream data.
-        QUIC_CODE_COUNT(quic_try_to_send_half_rtt_data_when_pto_fires);
-        return QuicConsumedData(0, false);
-      }
+    if (in_on_retransmission_time_out_ &&
+        coalesced_packet_.NumberOfPackets() == 0u) {
+      // PTO fires while handshake is not confirmed. Do not preempt handshake
+      // data with stream data.
+      QUIC_CODE_COUNT(quic_try_to_send_half_rtt_data_when_pto_fires);
+      return QuicConsumedData(0, false);
     }
     if (coalesced_packet_.ContainsPacketOfEncryptionLevel(ENCRYPTION_INITIAL) &&
         coalesced_packet_.NumberOfPackets() == 1u) {
diff --git a/quic/core/quic_connection_test.cc b/quic/core/quic_connection_test.cc
index a303afb..221fed8 100644
--- a/quic/core/quic_connection_test.cc
+++ b/quic/core/quic_connection_test.cc
@@ -15051,13 +15051,8 @@
 
   ASSERT_TRUE(connection_.GetRetransmissionAlarm()->IsSet());
   connection_.GetRetransmissionAlarm()->Fire();
-  if (GetQuicReloadableFlag(quic_donot_pto_half_rtt_data)) {
-    // Verify INITIAL and HANDSHAKE get retransmitted.
-    EXPECT_EQ(0x02020202u, writer_->final_bytes_of_last_packet());
-  } else {
-    // Application data preempts handshake data when PTO fires.
-    EXPECT_EQ(0x03030303u, writer_->final_bytes_of_last_packet());
-  }
+  // Verify INITIAL and HANDSHAKE get retransmitted.
+  EXPECT_EQ(0x02020202u, writer_->final_bytes_of_last_packet());
 }
 
 TEST_P(QuicConnectionTest, SendingZeroRttPacketsDoesNotPostponePTO) {
diff --git a/quic/core/quic_flags_list.h b/quic/core/quic_flags_list.h
index dbbffb0..65e511c 100644
--- a/quic/core/quic_flags_list.h
+++ b/quic/core/quic_flags_list.h
@@ -67,8 +67,6 @@
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_count_bytes_on_alternative_path_seperately, true)
 // If true, do not re-arm PTO while sending application data during handshake.
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_donot_rearm_pto_on_application_data_during_handshake, true)
-// If true, do not send stream data when PTO fires.
-QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_donot_pto_half_rtt_data, true)
 // If true, do not write stream data and control frames in the middle of packet processing. 
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_donot_write_mid_packet_processing, true)
 // If true, drop unsent PATH_RESPONSEs and rely on peer\'s retry.