Remove support for "npn-h2" and "npn-spdy/3.1" persisted values.

net/socket/next_proto.cc

 // Copyright 2016 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/socket/next_proto.h"
 
 namespace net {
 
 NextProto NextProtoFromString(base::StringPiece proto_string) {
   if (proto_string == "http1.1" || proto_string == "http/1.1")
     return kProtoHTTP11;
-  // "npn-h2" and "npn-spdy/3.1" are accepted here so that persisted
-  // settings with the old string can be loaded from disk.
-  // TODO(bnc):  Remove around 2016 December.
-  if (proto_string == "h2" || proto_string == "npn-h2" ||
-      proto_string == "npn-spdy/3.1") {
+  if (proto_string == "h2") {
     return kProtoHTTP2;
   }
   if (proto_string == "quic")
     return kProtoQUIC;
 
   return kProtoUnknown;
 }
 
 const char* NextProtoToString(NextProto next_proto) {
   switch (next_proto) {
     case kProtoHTTP11:
       return "http/1.1";
     case kProtoHTTP2:
       return "h2";
     case kProtoQUIC:
       return "quic";
     case kProtoUnknown:
       break;
   }
   return "unknown";
 }
 
 }  // namespace net