Componentize //chrome/browser/prefs/tracked.

chrome/browser/prefs/tracked/segregated_pref_store.h

-// Copyright 2014 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 CHROME_BROWSER_PREFS_TRACKED_SEGREGATED_PREF_STORE_H_
-#define CHROME_BROWSER_PREFS_TRACKED_SEGREGATED_PREF_STORE_H_
-
-#include <set>
-#include <string>
-
-#include "base/compiler_specific.h"
-#include "base/macros.h"
-#include "base/memory/ref_counted.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/observer_list.h"
-#include "base/prefs/persistent_pref_store.h"
-
-// Provides a unified PersistentPrefStore implementation that splits its storage
-// and retrieval between two underlying PersistentPrefStore instances: a set of
-// preference names is used to partition the preferences.
-//
-// Combines properties of the two stores as follows:
-//   * The unified read error will be:
-//                           Selected Store Error
-//    Default Store Error | NO_ERROR      | NO_FILE       | other selected |
-//               NO_ERROR | NO_ERROR      | NO_ERROR      | other selected |
-//               NO_FILE  | NO_FILE       | NO_FILE       | NO_FILE        |
-//          other default | other default | other default | other default  |
-//   * The unified initialization success, initialization completion, and
-//     read-only state are the boolean OR of the underlying stores' properties.
-class SegregatedPrefStore : public PersistentPrefStore {
- public:
-  // Creates an instance that delegates to |selected_pref_store| for the
-  // preferences named in |selected_pref_names| and to |default_pref_store|
-  // for all others. If an unselected preference is present in
-  // |selected_pref_store| (i.e. because it was previously selected) it will
-  // be migrated back to |default_pref_store| upon access via a non-const
-  // method.
-  // |on_initialization| will be invoked when both stores have been initialized,
-  // before observers of the SegregatedPrefStore store are notified.
-  SegregatedPrefStore(
-      const scoped_refptr<PersistentPrefStore>& default_pref_store,
-      const scoped_refptr<PersistentPrefStore>& selected_pref_store,
-      const std::set<std::string>& selected_pref_names);
-
-  // PrefStore implementation
-  void AddObserver(Observer* observer) override;
-  void RemoveObserver(Observer* observer) override;
-  bool HasObservers() const override;
-  bool IsInitializationComplete() const override;
-  bool GetValue(const std::string& key,
-                const base::Value** result) const override;
-
-  // WriteablePrefStore implementation
-  void SetValue(const std::string& key,
-                scoped_ptr<base::Value> value,
-                uint32 flags) override;
-  void RemoveValue(const std::string& key, uint32 flags) override;
-
-  // PersistentPrefStore implementation
-  bool GetMutableValue(const std::string& key, base::Value** result) override;
-  void ReportValueChanged(const std::string& key, uint32 flags) override;
-  void SetValueSilently(const std::string& key,
-                        scoped_ptr<base::Value> value,
-                        uint32 flags) override;
-  bool ReadOnly() const override;
-  PrefReadError GetReadError() const override;
-  PrefReadError ReadPrefs() override;
-  void ReadPrefsAsync(ReadErrorDelegate* error_delegate) override;
-  void CommitPendingWrite() override;
-  void SchedulePendingLossyWrites() override;
-
- private:
-  // Aggregates events from the underlying stores and synthesizes external
-  // events via |on_initialization|, |read_error_delegate_|, and |observers_|.
-  class AggregatingObserver : public PrefStore::Observer {
-   public:
-    explicit AggregatingObserver(SegregatedPrefStore* outer);
-
-    // PrefStore::Observer implementation
-    void OnPrefValueChanged(const std::string& key) override;
-    void OnInitializationCompleted(bool succeeded) override;
-
-   private:
-    SegregatedPrefStore* outer_;
-    int failed_sub_initializations_;
-    int successful_sub_initializations_;
-
-    DISALLOW_COPY_AND_ASSIGN(AggregatingObserver);
-  };
-
-  ~SegregatedPrefStore() override;
-
-  // Returns |selected_pref_store| if |key| is selected and |default_pref_store|
-  // otherwise.
-  PersistentPrefStore* StoreForKey(const std::string& key);
-  const PersistentPrefStore* StoreForKey(const std::string& key) const;
-
-  scoped_refptr<PersistentPrefStore> default_pref_store_;
-  scoped_refptr<PersistentPrefStore> selected_pref_store_;
-  std::set<std::string> selected_preference_names_;
-
-  scoped_ptr<PersistentPrefStore::ReadErrorDelegate> read_error_delegate_;
-  base::ObserverList<PrefStore::Observer, true> observers_;
-  AggregatingObserver aggregating_observer_;
-
-  DISALLOW_COPY_AND_ASSIGN(SegregatedPrefStore);
-};
-
-#endif  // CHROME_BROWSER_PREFS_TRACKED_SEGREGATED_PREF_STORE_H_