[SPDY] Add flag to turn on SPDY/3.1 (with per-session flow control)

net/socket/next_proto.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_SOCKET_NEXT_PROTO_H_
 #define NET_SOCKET_NEXT_PROTO_H_
 
 namespace net {
 
 // Next Protocol Negotiation (NPN), if successful, results in agreement on an
 // application-level string that specifies the application level protocol to
 // use over the TLS connection. NextProto enumerates the application level
 // protocols that we recognise.
 enum NextProto {
   kProtoUnknown = 0,
   kProtoHTTP11 = 1,
+
   kProtoSPDY1 = 2,
+  kProtoSPDYMinimumVersion = kProtoSPDY1,
   kProtoSPDY2 = 3,
   kProtoSPDY21 = 4,
   kProtoSPDY3 = 5,
   kProtoSPDY31 = 6,
+  kProtoSPDYMaximumVersion = kProtoSPDY31,
+
   kProtoMaximumVersion = 7,
 };
 
 }  // namespace net
 
 #endif  // NET_SOCKET_NEXT_PROTO_H_