Remove the last usages of PrefObserver outside of Prefs.

chrome/browser/tab_contents/spellchecker_submenu_observer_hunspell.cc

Index: chrome/browser/tab_contents/spellchecker_submenu_observer_hunspell.cc
diff --git a/chrome/browser/tab_contents/spellchecker_submenu_observer_hunspell.cc b/chrome/browser/tab_contents/spellchecker_submenu_observer_hunspell.cc
index f7e0233fc5bc05183d552f7862be0f865c3aadb5..7185ff0f60a4fed7eac699705cbf82aeba166ff9 100644
--- a/chrome/browser/tab_contents/spellchecker_submenu_observer_hunspell.cc
+++ b/chrome/browser/tab_contents/spellchecker_submenu_observer_hunspell.cc
@@ -153,8 +153,7 @@ void SpellCheckerSubMenuObserver::ExecuteCommand(int command_id) {
     if (profile && language < languages_.size()) {
       StringPrefMember dictionary_language;
       dictionary_language.Init(prefs::kSpellCheckDictionary,
-                               profile->GetPrefs(),
-                               NULL);
+                               profile->GetPrefs());
       dictionary_language.SetValue(languages_[language]);
     }
     return;