Add VersionOfIndex() to quic_protocol.h

net/quic/core/quic_protocol.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_protocol.h"
 
 #include "base/stl_util.h"
 #include "base/strings/string_number_conversions.h"
 #include "net/quic/core/quic_flags.h"
 #include "net/quic/core/quic_utils.h"
@@ skipping 180 matching lines @@
       if (FLAGS_quic_enable_version_35 && FLAGS_quic_enable_version_36) {
         filtered_versions.push_back(version);
       }
     } else {
       filtered_versions.push_back(version);
     }
   }
   return filtered_versions;
 }
 
+QuicVersionVector VersionOfIndex(const QuicVersionVector& versions, int index) {
+  QuicVersionVector version;
+  int version_count = versions.size();
+  if (index >= 0 && index < version_count) {
+    version.push_back(versions[index]);
+  } else {
+    version.push_back(QUIC_VERSION_UNSUPPORTED);
+  }
+  return version;
+}
+
 QuicTag QuicVersionToQuicTag(const QuicVersion version) {
   switch (version) {
     case QUIC_VERSION_30:
       return MakeQuicTag('Q', '0', '3', '0');
     case QUIC_VERSION_31:
       return MakeQuicTag('Q', '0', '3', '1');
     case QUIC_VERSION_32:
       return MakeQuicTag('Q', '0', '3', '2');
     case QUIC_VERSION_33:
       return MakeQuicTag('Q', '0', '3', '3');
@@ skipping 694 matching lines @@
       is_unackable(false),
       has_crypto_handshake(has_crypto_handshake),
       num_padding_bytes(num_padding_bytes),
       retransmission(0) {}
 
 TransmissionInfo::TransmissionInfo(const TransmissionInfo& other) = default;
 
 TransmissionInfo::~TransmissionInfo() {}
 
 }  // namespace net