net: Update the include paths of base/string_piece.h to its new location.

net/base/dns_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_BASE_DNS_UTIL_H_
 #define NET_BASE_DNS_UTIL_H_
 
 #include <string>
 
 #include "base/basictypes.h"
-#include "base/string_piece.h"
+#include "base/strings/string_piece.h"
 #include "net/base/net_export.h"
 
 namespace net {
 
 // DNSDomainFromDot - convert a domain string to DNS format. From DJB's
 // public domain DNS library.
 //
 //   dotted: a string in dotted form: "www.google.com"
 //   out: a result in DNS form: "\x03www\x06google\x03com\x00"
 NET_EXPORT_PRIVATE bool DNSDomainFromDot(const base::StringPiece& dotted,
                                          std::string* out);
 
 // DNSDomainToString converts a domain in DNS format to a dotted string.
 // Excludes the dot at the end.
 NET_EXPORT_PRIVATE std::string DNSDomainToString(
     const base::StringPiece& domain);
 
 // Returns true iff the given character is in the set of valid DNS label
 // characters as given in RFC 3490, 4.1, 3(a)
 NET_EXPORT_PRIVATE bool IsSTD3ASCIIValidCharacter(char c);
 
 // Returns the hostname by trimming the ending dot, if one exists.
 NET_EXPORT std::string TrimEndingDot(const base::StringPiece& host);
 
 }  // namespace net
 
 #endif  // NET_BASE_DNS_UTIL_H_