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.
5 #ifndef COMPONENTS_SYNC_PREFERENCES_SYNCED_PREF_CHANGE_REGISTRAR_H_
6 #define COMPONENTS_SYNC_PREFERENCES_SYNCED_PREF_CHANGE_REGISTRAR_H_
11 #include "base/callback.h"
12 #include "base/macros.h"
13 #include "components/sync_preferences/pref_service_syncable.h"
14 #include "components/sync_preferences/synced_pref_observer.h"
16 namespace sync_preferences {
18 // Manages the registration of one or more SyncedPrefObservers on a
19 // PrefServiceSyncable. This is modeled after base::PrefChangeRegistrar, and
20 // it should be used whenever it's necessary to determine whether a pref change
21 // has come from sync or from some other mechanism (managed, UI, external, etc.)
22 class SyncedPrefChangeRegistrar : public SyncedPrefObserver {
24 // Registered callbacks may optionally take a path argument.
25 // The boolean argument indicates whether (true) or not (false)
26 // the change was a result of syncing.
27 typedef base::Callback<void(bool)> ChangeCallback;
28 typedef base::Callback<void(const std::string&, bool)> NamedChangeCallback;
30 explicit SyncedPrefChangeRegistrar(PrefServiceSyncable* pref_service);
31 virtual ~SyncedPrefChangeRegistrar();
33 // Register an observer callback for sync change events on the pref at
34 // |path|. Only one callback may be registered per pref.
35 void Add(const char* path, const ChangeCallback& callback);
36 void Add(const char* path, const NamedChangeCallback& callback);
38 // Remove the registered observer for |path|.
39 void Remove(const char* path);
41 // Remove all registered observers.
44 // Indicates whether or not an observer is already registered for |path|.
45 bool IsObserved(const char* path) const;
48 // SyncedPrefObserver implementation
49 void OnSyncedPrefChanged(const std::string& path, bool from_sync) override;
51 typedef std::map<std::string, NamedChangeCallback> ObserverMap;
53 PrefServiceSyncable* pref_service_;
54 ObserverMap observers_;
56 DISALLOW_COPY_AND_ASSIGN(SyncedPrefChangeRegistrar);
59 } // namespace sync_preferences
61 #endif // COMPONENTS_SYNC_PREFERENCES_SYNCED_PREF_CHANGE_REGISTRAR_H_