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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_
58