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 BASE_PREFS_PREF_FILTER_H_ 6 #define BASE_PREFS_PREF_FILTER_H_ 7 8 #include <string> 9 10 #include "base/callback_forward.h" 11 #include "base/memory/scoped_ptr.h" 12 #include "base/prefs/base_prefs_export.h" 13 14 namespace base { 15 class DictionaryValue; 16 class Value; 17 } // namespace base 18 19 // Filters preferences as they are loaded from disk or updated at runtime. 20 // Currently supported only by JsonPrefStore. 21 class BASE_PREFS_EXPORT PrefFilter { 22 public: 23 // A callback to be invoked when |prefs| have been read (and possibly 24 // pre-modified) and are now ready to be handed back to this callback's 25 // builder. |schedule_write| indicates whether a write should be immediately 26 // scheduled (typically because the |prefs| were pre-modified). 27 typedef base::Callback<void(scoped_ptr<base::DictionaryValue> prefs, 28 bool schedule_write)> PostFilterOnLoadCallback; 29 30 virtual ~PrefFilter() {} 31 32 // This method is given ownership of the |pref_store_contents| read from disk 33 // before the underlying PersistentPrefStore gets to use them. It must hand 34 // them back via |post_filter_on_load_callback|, but may modify them first. 35 // Note: This method is asynchronous, which may make calls like 36 // PersistentPrefStore::ReadPrefs() asynchronous. The owner of filtered 37 // PersistentPrefStores should handle this to make the reads look synchronous 38 // to external users (see SegregatedPrefStore::ReadPrefs() for an example). 39 virtual void FilterOnLoad( 40 const PostFilterOnLoadCallback& post_filter_on_load_callback, 41 scoped_ptr<base::DictionaryValue> pref_store_contents) = 0; 42 43 // Receives notification when a pref store value is changed, before Observers 44 // are notified. 45 virtual void FilterUpdate(const std::string& path) = 0; 46 47 // Receives notification when the pref store is about to serialize data 48 // contained in |pref_store_contents| to a string. Modifications to 49 // |pref_store_contents| will be persisted to disk and also affect the 50 // in-memory state. 51 virtual void FilterSerializeData( 52 base::DictionaryValue* pref_store_contents) = 0; 53 }; 54 55 #endif // BASE_PREFS_PREF_FILTER_H_ 56
