fix clang warnings for chrome on android

net/http/http_util.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_HTTP_HTTP_UTIL_H_
 #define NET_HTTP_HTTP_UTIL_H_
 #pragma once
 
 #include <string>
 #include <vector>
@@ skipping 318 matching lines @@
     }
 
     // The value before unquoting (if any).
     std::string raw_value() const { return std::string(value_begin_,
                                                        value_end_); }
 
    private:
     HttpUtil::ValuesIterator props_;
     bool valid_;
 
-    std::string::const_iterator begin_;
-    std::string::const_iterator end_;
-
     std::string::const_iterator name_begin_;
     std::string::const_iterator name_end_;
 
     std::string::const_iterator value_begin_;
     std::string::const_iterator value_end_;
 
     // Do not store iterators into this string. The NameValuePairsIterator
     // is copyable/assignable, and if copied the copy's iterators would point
     // into the original's unquoted_value_ member.
     std::string unquoted_value_;
 
     bool value_is_quoted_;
   };
 };
 
 }  // namespace net
 
 #endif  // NET_HTTP_HTTP_UTIL_H_