Add more string_util functions to base namespace.

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

Index: chrome/browser/chromeos/login/test/oobe_base_test.cc
diff --git a/chrome/browser/chromeos/login/test/oobe_base_test.cc b/chrome/browser/chromeos/login/test/oobe_base_test.cc
index 85a807570e3740fa9e6976124ef30f00053f0985..379b393fd93620bbd1ecd127b429a11428090988 100644
--- a/chrome/browser/chromeos/login/test/oobe_base_test.cc
+++ b/chrome/browser/chromeos/login/test/oobe_base_test.cc
@@ -283,8 +283,8 @@ void OobeBaseTest::SetSignFormField(const std::string& field_id,
       "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);
 }