Revert of Unify enum NextProto and enum AlternateProtocol.

net/socket/next_proto.h

Index: net/socket/next_proto.h
diff --git a/net/socket/next_proto.h b/net/socket/next_proto.h
index 24807587c04219560facec749657f2486f2f535f..0cce71ff4599b7dd32e7ef3b23ad1157230a55c7 100644
--- a/net/socket/next_proto.h
+++ b/net/socket/next_proto.h
@@ -6,9 +6,6 @@
 #define NET_SOCKET_NEXT_PROTO_H_
 
 #include <vector>
-
-#include "base/strings/string_piece.h"
-#include "net/base/net_export.h"
 
 namespace net {
 
@@ -25,11 +22,6 @@
 // List of protocols to use for NPN, used for configuring HttpNetworkSessions.
 typedef std::vector<NextProto> NextProtoVector;
 
-NET_EXPORT_PRIVATE NextProto
-NextProtoFromString(base::StringPiece proto_string);
-
-NET_EXPORT_PRIVATE const char* NextProtoToString(NextProto next_proto);
-
 }  // namespace net
 
 #endif  // NET_SOCKET_NEXT_PROTO_H_