Deprecate quic_fix_key_update_on_first_packet

PiperOrigin-RevId: 370488745
Change-Id: I8b4810c606a70dc47968b85a1a7ca2b494c45a75
diff --git a/quic/core/quic_flags_list.h b/quic/core/quic_flags_list.h
index 8025ea3..46db046 100644
--- a/quic/core/quic_flags_list.h
+++ b/quic/core/quic_flags_list.h
@@ -47,7 +47,6 @@
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_encrypted_control_frames, false)
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_encrypted_goaway, true)
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_fix_dispatcher_sent_error_code, false)
-QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_fix_key_update_on_first_packet, true)
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_fix_on_stream_reset, true)
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_fix_stateless_reset, true)
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_fix_willing_and_able_to_write2, true)
diff --git a/quic/core/quic_framer.cc b/quic/core/quic_framer.cc
index c5de97b..db420b2 100644
--- a/quic/core/quic_framer.cc
+++ b/quic/core/quic_framer.cc
@@ -4872,10 +4872,8 @@
         if ((current_key_phase_first_received_packet_number_.IsInitialized() &&
              header.packet_number >
                  current_key_phase_first_received_packet_number_) ||
-            (GetQuicReloadableFlag(quic_fix_key_update_on_first_packet) &&
-             !current_key_phase_first_received_packet_number_.IsInitialized() &&
+            (!current_key_phase_first_received_packet_number_.IsInitialized() &&
              !key_update_performed_)) {
-          QUIC_RELOADABLE_FLAG_COUNT(quic_fix_key_update_on_first_packet);
           if (!next_decrypter_) {
             next_decrypter_ =
                 visitor_->AdvanceKeysAndCreateCurrentOneRttDecrypter();
diff --git a/quic/core/quic_framer_test.cc b/quic/core/quic_framer_test.cc
index 048a4b7..3b5f090 100644
--- a/quic/core/quic_framer_test.cc
+++ b/quic/core/quic_framer_test.cc
@@ -15230,7 +15230,6 @@
     // Key update is only used in QUIC+TLS.
     return;
   }
-  SetQuicReloadableFlag(quic_fix_key_update_on_first_packet, true);
   ASSERT_TRUE(framer_.version().KnowsWhichDecrypterToUse());
   // Doesn't use SetDecrypterLevel since we want to use StrictTaggingDecrypter
   // instead of TestDecrypter.
diff --git a/quic/core/quic_versions.cc b/quic/core/quic_versions.cc
index ab68ddd..185023f 100644
--- a/quic/core/quic_versions.cc
+++ b/quic/core/quic_versions.cc
@@ -599,7 +599,6 @@
 
 void QuicVersionInitializeSupportForIetfDraft() {
   // Enable necessary flags.
-  SetQuicReloadableFlag(quic_fix_key_update_on_first_packet, true);
 }
 
 void QuicEnableVersion(const ParsedQuicVersion& version) {