Remove QUIC_VERSION_21 from supported versions.

net/quic/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 <limits>
 #include <list>
@@ skipping 295 matching lines @@
 
 // This vector contains QUIC versions which we currently support.
 // This should be ordered such that the highest supported version is the first
 // element, with subsequent elements in descending order (versions can be
 // skipped as necessary).
 //
 // IMPORTANT: if you are adding to this list, follow the instructions at
 // http://sites/quic/adding-and-removing-versions
 static const QuicVersion kSupportedQuicVersions[] = {QUIC_VERSION_23,
                                                      QUIC_VERSION_22,
-                                                     QUIC_VERSION_21,
                                                      QUIC_VERSION_19};
 
 typedef std::vector<QuicVersion> QuicVersionVector;
 
 // Returns a vector of QUIC versions in kSupportedQuicVersions.
 NET_EXPORT_PRIVATE QuicVersionVector QuicSupportedVersions();
 
 // 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
@@ skipping 754 matching lines @@
   SequenceNumberList* all_transmissions;
   // In flight packets have not been abandoned or lost.
   bool in_flight;
   // True if the packet can never be acked, so it can be removed.
   bool is_unackable;
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_QUIC_PROTOCOL_H_