Introduce per-tab preferences service.

chrome/browser/prefs/pref_notifier_impl.h

 // Copyright (c) 2011 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 CHROME_BROWSER_PREFS_PREF_NOTIFIER_IMPL_H_
 #define CHROME_BROWSER_PREFS_PREF_NOTIFIER_IMPL_H_
 #pragma once
 
 #include <string>
 
 #include "base/hash_tables.h"
 #include "base/observer_list.h"
 #include "base/threading/non_thread_safe.h"
 #include "chrome/browser/prefs/pref_notifier.h"
 
 class PrefService;
 
 namespace content {
 class NotificationObserver;
 }
 
 // The PrefNotifier implementation used by the PrefService.
 class PrefNotifierImpl : public PrefNotifier,
                          public base::NonThreadSafe {
  public:
+  PrefNotifierImpl();
   explicit PrefNotifierImpl(PrefService* pref_service);
   virtual ~PrefNotifierImpl();
 
   // If the pref at the given path changes, we call the observer's Observe
   // method with PREF_CHANGED.
   void AddPrefObserver(const char* path, content::NotificationObserver* obs);
   void RemovePrefObserver(const char* path, content::NotificationObserver* obs);
 
   // PrefNotifier overrides.
   virtual void OnPreferenceChanged(const std::string& pref_name);
   virtual void OnInitializationCompleted(bool succeeded);
 
+  void SetPrefService(PrefService* pref_service);
+
  protected:
   // A map from pref names to a list of observers. Observers get fired in the
   // order they are added. These should only be accessed externally for unit
   // testing.
   typedef ObserverList<content::NotificationObserver> NotificationObserverList;
   typedef base::hash_map<std::string, NotificationObserverList*>
       PrefObserverMap;
 
   const PrefObserverMap* pref_observers() const { return &pref_observers_; }
 
  private:
   // For the given pref_name, fire any observer of the pref. Virtual so it can
   // be mocked for unit testing.
   virtual void FireObservers(const std::string& path);
 
   // Weak reference; the notifier is owned by the PrefService.
   PrefService* pref_service_;
 
   PrefObserverMap pref_observers_;
 
   DISALLOW_COPY_AND_ASSIGN(PrefNotifierImpl);
 };
 
 #endif  // CHROME_BROWSER_PREFS_PREF_NOTIFIER_IMPL_H_