chrome/browser/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 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.)
  19 class 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_