Remove PrefObserver usage, batch 3.

base/prefs/public/pref_change_registrar.h

 // Copyright (c) 2010 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.
 
 #ifndef BASE_PREFS_PUBLIC_PREF_CHANGE_REGISTRAR_H_
 #define BASE_PREFS_PUBLIC_PREF_CHANGE_REGISTRAR_H_
 
 #include <map>
 #include <string>
 
@@ skipping 43 matching lines @@
 
   // Returns true if no pref observers are registered.
   bool IsEmpty() const;
 
   // Check whether |pref| is in the set of preferences being observed.
   bool IsObserved(const std::string& pref);
 
   // Check whether any of the observed preferences has the managed bit set.
   bool IsManaged();
 
+  // Return the PrefServiceBase for this registrar.
+  PrefServiceBase* prefs();
+
  private:
   // PrefObserver:
   virtual void OnPreferenceChanged(PrefServiceBase* service,
                                    const std::string& pref_name) OVERRIDE;
 
   static void InvokeUnnamedCallback(const base::Closure& callback,
                                     const std::string& pref_name);
 
   typedef std::map<std::string, NamedChangeCallback> ObserverMap;
 
   ObserverMap observers_;
   PrefServiceBase* service_;
 
   DISALLOW_COPY_AND_ASSIGN(PrefChangeRegistrar);
 };
 
 #endif  // BASE_PREFS_PUBLIC_PREF_CHANGE_REGISTRAR_H_