Add language_prefs namespace to language_preferences.h.

chrome/browser/chromeos/options/language_pinyin_config_view.h

Index: chrome/browser/chromeos/options/language_pinyin_config_view.h
diff --git a/chrome/browser/chromeos/options/language_pinyin_config_view.h b/chrome/browser/chromeos/options/language_pinyin_config_view.h
index 2e01e18fcbe8e321757e8986507f28e1cd954601..a72be04defbd9f2c285ee4ba7c5dc785fc768ec0 100644
--- a/chrome/browser/chromeos/options/language_pinyin_config_view.h
+++ b/chrome/browser/chromeos/options/language_pinyin_config_view.h
@@ -65,12 +65,14 @@ class LanguagePinyinConfigView : public views::ButtonListener,
   // Updates the pinyin checkboxes.
   void NotifyPrefChanged();
 
-  BooleanPrefMember pinyin_boolean_prefs_[kNumPinyinBooleanPrefs];
+  BooleanPrefMember pinyin_boolean_prefs_[
+      language_prefs::kNumPinyinBooleanPrefs];
   // TODO(yusukes): Support integer prefs if needed.
   views::View* contents_;
 
   // A checkboxes for Pinyin.
-  views::Checkbox* pinyin_boolean_checkboxes_[kNumPinyinBooleanPrefs];
+  views::Checkbox* pinyin_boolean_checkboxes_[
+      language_prefs::kNumPinyinBooleanPrefs];
 
   struct DoublePinyinSchemaPrefAndAssociatedCombobox {
     IntegerPrefMember multiple_choice_pref;