Revert of Unify enum NextProto and enum AlternateProtocol.

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") {
-    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