Add more string_util functions to base namespace.

chrome/browser/chromeos/login/test/oobe_base_test.cc

 // Copyright 2014 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/login/test/oobe_base_test.h"
 
 #include "base/command_line.h"
 #include "base/json/json_file_value_serializer.h"
 #include "base/message_loop/message_loop.h"
 #include "base/path_service.h"
@@ skipping 265 matching lines @@
 }
 
 void OobeBaseTest::SetSignFormField(const std::string& field_id,
                                     const std::string& field_value) {
   std::string js =
       "(function(){"
       "document.getElementById('$FieldId').value = '$FieldValue';"
       "var e = new Event('input');"
       "document.getElementById('$FieldId').dispatchEvent(e);"
       "})();";
-  ReplaceSubstringsAfterOffset(&js, 0, "$FieldId", field_id);
-  ReplaceSubstringsAfterOffset(&js, 0, "$FieldValue", field_value);
+  base::ReplaceSubstringsAfterOffset(&js, 0, "$FieldId", field_id);
+  base::ReplaceSubstringsAfterOffset(&js, 0, "$FieldValue", field_value);
   ExecuteJsInSigninFrame(js);
 }
 
 }  // namespace chromeos