overlay_persistent_pref_store.h revision 72a454cd3513ac24fbdd0e0cb9ad70b86a99b801 
1// Copyright (c) 2011 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef CHROME_BROWSER_PREFS_OVERLAY_PERSISTENT_PREF_STORE_H_
6#define CHROME_BROWSER_PREFS_OVERLAY_PERSISTENT_PREF_STORE_H_
7#pragma once
8
9#include <string>
10
11#include "base/basictypes.h"
12#include "base/observer_list.h"
13#include "base/ref_counted.h"
14#include "chrome/browser/prefs/pref_value_map.h"
15#include "chrome/common/persistent_pref_store.h"
16
17// PersistentPrefStore that directs all write operations into a in-memory
18// PrefValueMap. Read operations are first answered by the PrefValueMap.
19// If the PrefValueMap does not contain a value for the requested key,
20// the look-up is passed on to an underlying PersistentPrefStore |underlay_|.
21class OverlayPersistentPrefStore : public PersistentPrefStore,
22                                   public PrefStore::Observer {
23 public:
24  explicit OverlayPersistentPrefStore(PersistentPrefStore* underlay);
25  virtual ~OverlayPersistentPrefStore();
26
27  // Methods of PrefStore.
28  virtual void AddObserver(PrefStore::Observer* observer);
29  virtual void RemoveObserver(PrefStore::Observer* observer);
30  virtual bool IsInitializationComplete() const;
31  virtual ReadResult GetValue(const std::string& key, Value** result) const;
32
33  // Methods of PersistentPrefStore.
34  virtual void SetValue(const std::string& key, Value* value);
35  virtual void SetValueSilently(const std::string& key, Value* value);
36  virtual void RemoveValue(const std::string& key);
37  virtual bool ReadOnly() const;
38  virtual PrefReadError ReadPrefs();
39  virtual bool WritePrefs();
40  virtual void ScheduleWritePrefs();
41
42 private:
43  // Methods of PrefStore::Observer.
44  virtual void OnPrefValueChanged(const std::string& key);
45  virtual void OnInitializationCompleted();
46
47  ObserverList<PrefStore::Observer, true> observers_;
48  PrefValueMap overlay_;
49  scoped_refptr<PersistentPrefStore> underlay_;
50
51  DISALLOW_COPY_AND_ASSIGN(OverlayPersistentPrefStore);
52};
53
54#endif  // CHROME_BROWSER_PREFS_OVERLAY_PERSISTENT_PREF_STORE_H_
55