Use a direct include of strings headers in chrome/browser/chromeos/.

chrome/browser/chromeos/cros/network_library_impl_base.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 "chrome/browser/chromeos/cros/network_library_impl_base.h"
 
 #include "base/bind.h"
 #include "base/json/json_writer.h"
 #include "base/memory/scoped_vector.h"
 #include "base/stl_util.h"
-#include "base/string_util.h"
+#include "base/strings/string_util.h"
 #include "chrome/browser/chromeos/cros/network_constants.h"
 #include "chrome/browser/chromeos/login/user_manager.h"
 #include "chrome/browser/chromeos/net/onc_utils.h"
 #include "chrome/browser/chromeos/network_login_observer.h"
 #include "chromeos/network/network_state_handler.h"
 #include "chromeos/network/network_ui_data.h"
 #include "chromeos/network/onc/onc_constants.h"
 #include "chromeos/network/onc/onc_normalizer.h"
 #include "chromeos/network/onc/onc_signature.h"
 #include "chromeos/network/onc/onc_translator.h"
@@ skipping 1657 matching lines @@
   GetTpmInfo();
   return tpm_slot_;
 }
 
 const std::string& NetworkLibraryImplBase::GetTpmPin() {
   GetTpmInfo();
   return tpm_pin_;
 }
 
 }  // namespace chromeos