Add language_prefs namespace to language_preferences.h.

chrome/browser/chromeos/dom_ui/language_options_util.h

Index: chrome/browser/chromeos/dom_ui/language_options_util.h
diff --git a/chrome/browser/chromeos/dom_ui/language_options_util.h b/chrome/browser/chromeos/dom_ui/language_options_util.h
index 3cfd5646c854d01d75e1bbb58ccff54185646e77..1723d2dfa8bdd60f641c13dead2f1b2db381fa11 100644
--- a/chrome/browser/chromeos/dom_ui/language_options_util.h
+++ b/chrome/browser/chromeos/dom_ui/language_options_util.h
@@ -62,10 +62,10 @@ namespace chromeos {
 // Creates a multiple choice list from the given preference.
 template <typename T>
 ListValue* CreateMultipleChoiceList(
-    const LanguageMultipleChoicePreference<T>& preference) {
+    const language_prefs::LanguageMultipleChoicePreference<T>& preference) {
   int list_length = 0;
   for (size_t i = 0;
-       i < LanguageMultipleChoicePreference<T>::kMaxItems;
+       i < language_prefs::LanguageMultipleChoicePreference<T>::kMaxItems;
        ++i) {
     if (preference.values_and_ids[i].item_message_id == 0)
       break;