Deprecate gfe2_restart_flag_quic_receive_ecn3.

PiperOrigin-RevId: 604725307
diff --git a/quiche/quic/core/quic_connection_test.cc b/quiche/quic/core/quic_connection_test.cc
index b767764..ac61c60 100644
--- a/quiche/quic/core/quic_connection_test.cc
+++ b/quiche/quic/core/quic_connection_test.cc
@@ -16929,23 +16929,17 @@
     QuicConnectionPeer::SendPing(&connection_);
   }
   QuicConnectionStats stats = connection_.GetStats();
-  if (GetQuicRestartFlag(quic_receive_ecn3)) {
-    ASSERT_TRUE(ack_frame.ecn_counters.has_value());
-    EXPECT_EQ(ack_frame.ecn_counters->ect0, 1);
-    EXPECT_EQ(stats.num_ack_frames_sent_with_ecn,
-              connection_.version().HasIetfQuicFrames() ? 1 : 0);
-  } else {
-    EXPECT_FALSE(ack_frame.ecn_counters.has_value());
-    EXPECT_EQ(stats.num_ack_frames_sent_with_ecn, 0);
-  }
+  ASSERT_TRUE(ack_frame.ecn_counters.has_value());
+  EXPECT_EQ(ack_frame.ecn_counters->ect0, 1);
+  EXPECT_EQ(stats.num_ack_frames_sent_with_ecn,
+            connection_.version().HasIetfQuicFrames() ? 1 : 0);
   EXPECT_EQ(stats.num_ecn_marks_received.ect0, 1);
   EXPECT_EQ(stats.num_ecn_marks_received.ect1, 0);
   EXPECT_EQ(stats.num_ecn_marks_received.ce, 0);
 }
 
 TEST_P(QuicConnectionTest, EcnMarksCoalescedPacket) {
-  if (!connection_.version().CanSendCoalescedPackets() ||
-      !GetQuicRestartFlag(quic_receive_ecn3)) {
+  if (!connection_.version().CanSendCoalescedPackets()) {
     return;
   }
   QuicCryptoFrame crypto_frame1{ENCRYPTION_HANDSHAKE, 0, "foo"};
@@ -16997,21 +16991,15 @@
     EXPECT_TRUE(ack_frame.ecn_counters.has_value());
     EXPECT_EQ(ack_frame.ecn_counters->ect0, 1);
   }
-  if (GetQuicRestartFlag(quic_receive_ecn3)) {
-    EXPECT_EQ(stats.num_ecn_marks_received.ect0, 2);
-    EXPECT_EQ(stats.num_ack_frames_sent_with_ecn,
-              connection_.version().HasIetfQuicFrames() ? 2 : 0);
-  } else {
-    EXPECT_EQ(stats.num_ecn_marks_received.ect0, 0);
-    EXPECT_EQ(stats.num_ack_frames_sent_with_ecn, 0);
-  }
+  EXPECT_EQ(stats.num_ecn_marks_received.ect0, 2);
+  EXPECT_EQ(stats.num_ack_frames_sent_with_ecn,
+            connection_.version().HasIetfQuicFrames() ? 2 : 0);
   EXPECT_EQ(stats.num_ecn_marks_received.ect1, 0);
   EXPECT_EQ(stats.num_ecn_marks_received.ce, 0);
 }
 
 TEST_P(QuicConnectionTest, EcnMarksUndecryptableCoalescedPacket) {
-  if (!connection_.version().CanSendCoalescedPackets() ||
-      !GetQuicRestartFlag(quic_receive_ecn3)) {
+  if (!connection_.version().CanSendCoalescedPackets()) {
     return;
   }
   // SetFromConfig is always called after construction from InitializeSession.
@@ -17126,11 +17114,9 @@
   EXPECT_EQ(ack_frame.ecn_counters->ect0,
             connection_.SupportsMultiplePacketNumberSpaces() ? 1 : 2);
   QuicConnectionStats stats = connection_.GetStats();
-  EXPECT_EQ(stats.num_ecn_marks_received.ect0,
-            GetQuicRestartFlag(quic_receive_ecn3) ? 2 : 0);
+  EXPECT_EQ(stats.num_ecn_marks_received.ect0, 2);
   EXPECT_EQ(stats.num_ecn_marks_received.ect1, 0);
-  EXPECT_EQ(stats.num_ecn_marks_received.ce,
-            GetQuicRestartFlag(quic_receive_ecn3) ? 1 : 0);
+  EXPECT_EQ(stats.num_ecn_marks_received.ce, 1);
 }
 
 TEST_P(QuicConnectionTest, ReceivedPacketInfoDefaults) {