1// Copyright 2013 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_SYNCED_PREF_CHANGE_REGISTRAR_H_
6#define CHROME_BROWSER_PREFS_SYNCED_PREF_CHANGE_REGISTRAR_H_
7
8#include <map>
9#include <string>
10
11#include "base/callback.h"
12#include "chrome/browser/prefs/pref_service_syncable.h"
13#include "chrome/browser/prefs/synced_pref_observer.h"
14
15// Manages the registration of one or more SyncedPrefObservers on a
16// PrefServiceSyncable. This is modeled after base::PrefChangeRegistrar, and
17// it should be used whenever it's necessary to determine whether a pref change
18// has come from sync or from some other mechanism (managed, UI, external, etc.)
19class SyncedPrefChangeRegistrar : public SyncedPrefObserver {
20 public:
21  // Registered callbacks may optionally take a path argument.
22  // The boolean argument indicates whether (true) or not (false)
23  // the change was a result of syncing.
24  typedef base::Callback<void(bool)> ChangeCallback;
25  typedef base::Callback<void(const std::string&, bool)> NamedChangeCallback;
26
27  explicit SyncedPrefChangeRegistrar(PrefServiceSyncable* pref_service);
28  virtual ~SyncedPrefChangeRegistrar();
29
30  // Register an observer callback for sync change events on the pref at
31  // |path|. Only one callback may be registered per pref.
32  void Add(const char* path, const ChangeCallback& callback);
33  void Add(const char* path, const NamedChangeCallback& callback);
34
35  // Remove the registered observer for |path|.
36  void Remove(const char* path);
37
38  // Remove all registered observers.
39  void RemoveAll();
40
41  // Indicates whether or not an observer is already registered for |path|.
42  bool IsObserved(const char* path) const;
43
44 private:
45  // SyncedPrefObserver implementation
46  virtual void OnSyncedPrefChanged(const std::string& path, bool from_sync)
47      OVERRIDE;
48
49  typedef std::map<std::string, NamedChangeCallback> ObserverMap;
50
51  PrefServiceSyncable* pref_service_;
52  ObserverMap observers_;
53
54  DISALLOW_COPY_AND_ASSIGN(SyncedPrefChangeRegistrar);
55};
56
57#endif  // CHROME_BROWSER_PREFS_SYNCED_PREF_CHANGE_REGISTRAR_H_
58