In QUIC version >= 38, enables random padding of size [1, 256]

net/quic/core/quic_packet_creator.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/quic/core/quic_packet_creator.h"
 
 #include <algorithm>
 #include <cstdint>
 
 #include "base/macros.h"
 #include "net/quic/core/crypto/crypto_protocol.h"
 #include "net/quic/core/quic_data_writer.h"
 #include "net/quic/core/quic_flags.h"
 #include "net/quic/core/quic_utils.h"
 #include "net/quic/platform/api/quic_aligned.h"
 #include "net/quic/platform/api/quic_bug_tracker.h"
+#include "net/quic/platform/api/quic_flag_utils.h"
 #include "net/quic/platform/api/quic_logging.h"
 #include "net/quic/platform/api/quic_string_piece.h"
 
 using std::string;
 
 // If true, enforce that QUIC CHLOs fit in one packet.
 bool FLAGS_quic_enforce_single_packet_chlo = true;
 
 namespace net {
 
@@ skipping 611 matching lines @@
     return;
   }
 
   if (needs_full_padding_) {
     // Full padding does not consume pending padding bytes.
     packet_.num_padding_bytes = -1;
   } else {
     packet_.num_padding_bytes =
         std::min<int16_t>(pending_padding_bytes_, BytesFree());
     pending_padding_bytes_ -= packet_.num_padding_bytes;
+    QUIC_FLAG_COUNT(quic_reloadable_flag_quic_enable_random_padding);
   }
 
   bool success =
       AddFrame(QuicFrame(QuicPaddingFrame(packet_.num_padding_bytes)), false);
   DCHECK(success);
 }
 
 bool QuicPacketCreator::IncludeNonceInPublicHeader() {
   return have_diversification_nonce_ &&
          packet_.encryption_level == ENCRYPTION_INITIAL;
 }
 
 void QuicPacketCreator::AddPendingPadding(QuicByteCount size) {
   pending_padding_bytes_ += size;
 }
 
 }  // namespace net