Revert of Move base/prefs to components/prefs

components/prefs/pref_filter.h

-// 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 BASE_PREFS_PREF_FILTER_H_
-#define BASE_PREFS_PREF_FILTER_H_
-
-#include <string>
-
-#include "base/callback_forward.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/prefs/base_prefs_export.h"
-
-namespace base {
-class DictionaryValue;
-class Value;
-}  // namespace base
-
-// Filters preferences as they are loaded from disk or updated at runtime.
-// Currently supported only by JsonPrefStore.
-class BASE_PREFS_EXPORT PrefFilter {
- public:
-  // A callback to be invoked when |prefs| have been read (and possibly
-  // pre-modified) and are now ready to be handed back to this callback's
-  // builder. |schedule_write| indicates whether a write should be immediately
-  // scheduled (typically because the |prefs| were pre-modified).
-  typedef base::Callback<void(scoped_ptr<base::DictionaryValue> prefs,
-                              bool schedule_write)> PostFilterOnLoadCallback;
-
-  virtual ~PrefFilter() {}
-
-  // This method is given ownership of the |pref_store_contents| read from disk
-  // before the underlying PersistentPrefStore gets to use them. It must hand
-  // them back via |post_filter_on_load_callback|, but may modify them first.
-  // Note: This method is asynchronous, which may make calls like
-  // PersistentPrefStore::ReadPrefs() asynchronous. The owner of filtered
-  // PersistentPrefStores should handle this to make the reads look synchronous
-  // to external users (see SegregatedPrefStore::ReadPrefs() for an example).
-  virtual void FilterOnLoad(
-      const PostFilterOnLoadCallback& post_filter_on_load_callback,
-      scoped_ptr<base::DictionaryValue> pref_store_contents) = 0;
-
-  // Receives notification when a pref store value is changed, before Observers
-  // are notified.
-  virtual void FilterUpdate(const std::string& path) = 0;
-
-  // Receives notification when the pref store is about to serialize data
-  // contained in |pref_store_contents| to a string. Modifications to
-  // |pref_store_contents| will be persisted to disk and also affect the
-  // in-memory state.
-  virtual void FilterSerializeData(
-      base::DictionaryValue* pref_store_contents) = 0;
-};
-
-#endif  // BASE_PREFS_PREF_FILTER_H_