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// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef COMPONENTS_SYNCABLE_PREFS_SYNCED_PREF_CHANGE_REGISTRAR_H_
#define COMPONENTS_SYNCABLE_PREFS_SYNCED_PREF_CHANGE_REGISTRAR_H_
#include <map>
#include <string>
#include "base/callback.h"
#include "base/macros.h"
#include "components/syncable_prefs/pref_service_syncable.h"
#include "components/syncable_prefs/synced_pref_observer.h"
namespace syncable_prefs {
// Manages the registration of one or more SyncedPrefObservers on a
// PrefServiceSyncable. This is modeled after base::PrefChangeRegistrar, and
// it should be used whenever it's necessary to determine whether a pref change
// has come from sync or from some other mechanism (managed, UI, external, etc.)
class SyncedPrefChangeRegistrar : public SyncedPrefObserver {
public:
// Registered callbacks may optionally take a path argument.
// The boolean argument indicates whether (true) or not (false)
// the change was a result of syncing.
typedef base::Callback<void(bool)> ChangeCallback;
typedef base::Callback<void(const std::string&, bool)> NamedChangeCallback;
explicit SyncedPrefChangeRegistrar(PrefServiceSyncable* pref_service);
virtual ~SyncedPrefChangeRegistrar();
// Register an observer callback for sync change events on the pref at
// |path|. Only one callback may be registered per pref.
void Add(const char* path, const ChangeCallback& callback);
void Add(const char* path, const NamedChangeCallback& callback);
// Remove the registered observer for |path|.
void Remove(const char* path);
// Remove all registered observers.
void RemoveAll();
// Indicates whether or not an observer is already registered for |path|.
bool IsObserved(const char* path) const;
private:
// SyncedPrefObserver implementation
void OnSyncedPrefChanged(const std::string& path, bool from_sync) override;
typedef std::map<std::string, NamedChangeCallback> ObserverMap;
PrefServiceSyncable* pref_service_;
ObserverMap observers_;
DISALLOW_COPY_AND_ASSIGN(SyncedPrefChangeRegistrar);
};
} // namespace syncable_prefs
#endif // COMPONENTS_SYNCABLE_PREFS_SYNCED_PREF_CHANGE_REGISTRAR_H_
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