components/syncable_prefs/synced_pref_change_registrar.h

   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 COMPONENTS_SYNCABLE_PREFS_SYNCED_PREF_CHANGE_REGISTRAR_H_
   6 #define COMPONENTS_SYNCABLE_PREFS_SYNCED_PREF_CHANGE_REGISTRAR_H_
   7
   8 #include <map>
   9 #include <string>
  10
  11 #include "base/callback.h"
  12 #include "components/syncable_prefs/pref_service_syncable.h"
  13 #include "components/syncable_prefs/synced_pref_observer.h"
  14
  15 namespace syncable_prefs {
  16
  17 // Manages the registration of one or more SyncedPrefObservers on a
  18 // PrefServiceSyncable. This is modeled after base::PrefChangeRegistrar, and
  19 // it should be used whenever it's necessary to determine whether a pref change
  20 // has come from sync or from some other mechanism (managed, UI, external, etc.)
  21 class SyncedPrefChangeRegistrar : public SyncedPrefObserver {
  22  public:
  23   // Registered callbacks may optionally take a path argument.
  24   // The boolean argument indicates whether (true) or not (false)
  25   // the change was a result of syncing.
  26   typedef base::Callback<void(bool)> ChangeCallback;
  27   typedef base::Callback<void(const std::string&, bool)> NamedChangeCallback;
  28
  29   explicit SyncedPrefChangeRegistrar(PrefServiceSyncable* pref_service);
  30   virtual ~SyncedPrefChangeRegistrar();
  31
  32   // Register an observer callback for sync change events on the pref at
  33   // |path|. Only one callback may be registered per pref.
  34   void Add(const char* path, const ChangeCallback& callback);
  35   void Add(const char* path, const NamedChangeCallback& callback);
  36
  37   // Remove the registered observer for |path|.
  38   void Remove(const char* path);
  39
  40   // Remove all registered observers.
  41   void RemoveAll();
  42
  43   // Indicates whether or not an observer is already registered for |path|.
  44   bool IsObserved(const char* path) const;
  45
  46  private:
  47   // SyncedPrefObserver implementation
  48   void OnSyncedPrefChanged(const std::string& path, bool from_sync) override;
  49
  50   typedef std::map<std::string, NamedChangeCallback> ObserverMap;
  51
  52   PrefServiceSyncable* pref_service_;
  53   ObserverMap observers_;
  54
  55   DISALLOW_COPY_AND_ASSIGN(SyncedPrefChangeRegistrar);
  56 };
  57
  58 }  // namespace syncable_prefs
  59
  60 #endif  // COMPONENTS_SYNCABLE_PREFS_SYNCED_PREF_CHANGE_REGISTRAR_H_