Remove PrefObserver usage, batch 3.

base/prefs/public/pref_change_registrar.cc

 // 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.
 
 #include "base/prefs/public/pref_change_registrar.h"
 
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/prefs/public/pref_service_base.h"
 
@@ skipping 73 matching lines @@
 void PrefChangeRegistrar::OnPreferenceChanged(PrefServiceBase* service,
                                               const std::string& pref) {
   if (IsObserved(pref))
     observers_[pref].Run(pref);
 }
 
 void PrefChangeRegistrar::InvokeUnnamedCallback(const base::Closure& callback,
                                                 const std::string& pref_name) {
   callback.Run();
 }
+
+PrefServiceBase* PrefChangeRegistrar::prefs() {
+  return service_;
+}