[net/http auth] Use strings to identify authentication schemes.

net/http/http_auth_scheme_set.h

+// Copyright 2015 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_HTTP_HTTP_AUTH_SCHEME_SET_H_
+#define NET_HTTP_HTTP_AUTH_SCHEME_SET_H_
+
+#include <set>
+#include <string>
+
+#include "net/base/net_export.h"
+
+namespace net {
+
+// A set of HTTP auth schemes.
+class NET_EXPORT HttpAuthSchemeSet {
+ public:
+  HttpAuthSchemeSet();
+  ~HttpAuthSchemeSet();
+
+  // |scheme| needs to be normalized.
+  void Add(const std::string& scheme);
+
+  // |scheme| needs to be normalized.
+  bool Contains(const std::string& scheme) const;
+
+ private:
+  std::set<std::string> schemes_;
+};
+
+}  // namespace net
+
+#endif  // NET_HTTP_HTTP_AUTH_SCHEME_SET_H_