Add VersionOfIndex() to quic_protocol.h

net/quic/core/quic_protocol.h

 // 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.
 
 #ifndef NET_QUIC_QUIC_PROTOCOL_H_
 #define NET_QUIC_QUIC_PROTOCOL_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 376 matching lines @@
 typedef std::vector<QuicVersion> QuicVersionVector;
 
 // Returns a vector of QUIC versions in kSupportedQuicVersions.
 NET_EXPORT_PRIVATE QuicVersionVector QuicSupportedVersions();
 
 // Returns a vector of QUIC versions from |versions| which exclude any versions
 // which are disabled by flags.
 NET_EXPORT_PRIVATE QuicVersionVector
 FilterSupportedVersions(QuicVersionVector versions);
 
+// Returns QUIC version of |index| in result of |versions|. Returns
+// QUIC_VERSION_UNSUPPORTED if |index| is out of bounds.
+NET_EXPORT_PRIVATE QuicVersionVector
+VersionOfIndex(const QuicVersionVector& versions, int index);
+
 // QuicTag is written to and read from the wire, but we prefer to use
 // the more readable QuicVersion at other levels.
 // Helper function which translates from a QuicVersion to a QuicTag. Returns 0
 // if QuicVersion is unsupported.
 NET_EXPORT_PRIVATE QuicTag QuicVersionToQuicTag(const QuicVersion version);
 
 // Returns appropriate QuicVersion from a QuicTag.
 // Returns QUIC_VERSION_UNSUPPORTED if version_tag cannot be understood.
 NET_EXPORT_PRIVATE QuicVersion QuicTagToQuicVersion(const QuicTag version_tag);
 
@@ skipping 1128 matching lines @@
       : iov(iov), iov_count(iov_count), total_length(total_length) {}
 
   const struct iovec* iov;
   const int iov_count;
   const size_t total_length;
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_QUIC_PROTOCOL_H_