Use a direct include of strings headers in chromeos/.

chromeos/network/network_util.cc

 // 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.
 
 #include "chromeos/network/network_util.h"
 
-#include "base/stringprintf.h"
 #include "base/strings/string_tokenizer.h"
+#include "base/strings/stringprintf.h"
 
 namespace chromeos {
 
 SMS::SMS() : validity(0), msgclass(0) {
 }
 
 SMS::~SMS() {
 }
 
 WifiAccessPoint::WifiAccessPoint()
@@ skipping 68 matching lines @@
     }
     count++;
   }
   if (count < 4)
     return -1;
   return prefix_length;
 }
 
 }  // namespace network_util
 }  // namespace chromeos