Take out and generalize user prefs overriding from IncognitoUserPrefStore.

chrome/browser/prefs/overlay_user_pref_store.h

 // Copyright (c) 2011 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_INCOGNITO_USER_PREF_STORE_H_
-#define CHROME_BROWSER_PREFS_INCOGNITO_USER_PREF_STORE_H_
+#ifndef CHROME_BROWSER_PREFS_OVERLAY_USER_PREF_STORE_H_
+#define CHROME_BROWSER_PREFS_OVERLAY_USER_PREF_STORE_H_
 #pragma once
 
 #include <string>
 
 #include "base/basictypes.h"
+#include "base/hash_tables.h"

[Mattias Nissler (ping if slow), 2011/11/14 12:04:55]

remove this and instead #include <map>

[mnaganov (inactive), 2011/11/14 12:07:31]

Done.

 #include "base/memory/ref_counted.h"
 #include "base/observer_list.h"
 #include "chrome/browser/prefs/pref_value_map.h"
 #include "chrome/common/persistent_pref_store.h"
 
 // PersistentPrefStore that directs all write operations into an in-memory
 // PrefValueMap. Read operations are first answered by the PrefValueMap.
 // If the PrefValueMap does not contain a value for the requested key,
 // the look-up is passed on to an underlying PersistentPrefStore |underlay_|.
-class IncognitoUserPrefStore : public PersistentPrefStore,
-                               public PrefStore::Observer {
+class OverlayUserPrefStore : public PersistentPrefStore,
+                             public PrefStore::Observer {
  public:
-  explicit IncognitoUserPrefStore(PersistentPrefStore* underlay);
-  virtual ~IncognitoUserPrefStore();
+  explicit OverlayUserPrefStore(PersistentPrefStore* underlay);
+  virtual ~OverlayUserPrefStore();
 
   // Returns true if a value has been set for the |key| in this
-  // IncognitoUserPrefStore, i.e. if it potentially overrides a value
+  // OverlayUserPrefStore, i.e. if it potentially overrides a value
   // from the |underlay_|.
   virtual bool IsSetInOverlay(const std::string& key) const;
 
   // Methods of PrefStore.
   virtual void AddObserver(PrefStore::Observer* observer);
   virtual void RemoveObserver(PrefStore::Observer* observer);
   virtual bool IsInitializationComplete() const;
   virtual ReadResult GetValue(const std::string& key,
                               const base::Value** result) const;
 
   // Methods of PersistentPrefStore.
   virtual ReadResult GetMutableValue(const std::string& key,
                                      base::Value** result);
   virtual void SetValue(const std::string& key, base::Value* value);
   virtual void SetValueSilently(const std::string& key, base::Value* value);
   virtual void RemoveValue(const std::string& key);
   virtual bool ReadOnly() const;
   virtual PrefReadError ReadPrefs();
   virtual void ReadPrefsAsync(ReadErrorDelegate* delegate);
   virtual bool WritePrefs();
   virtual void ScheduleWritePrefs();
   virtual void CommitPendingWrite();
   virtual void ReportValueChanged(const std::string& key);
 
+ protected:
+  void RegisterOverlayProperty(const std::string& key);
+  void RegisterOverlayProperty(const std::string& overlay_key,
+                               const std::string& underlay_key);
+
  private:
+  friend class OverlayUserPrefStoreTest;
+
+  typedef std::map<std::string, std::string> NamesMap;
+
   // Methods of PrefStore::Observer.
   virtual void OnPrefValueChanged(const std::string& key);
   virtual void OnInitializationCompleted(bool succeeded);
 
+  const std::string& GetOverlayKey(const std::string& underlay_key) const;
+  const std::string& GetUnderlayKey(const std::string& overlay_key) const;
+
   // Returns true if |key| corresponds to a preference that shall be stored in
-  // an in-memory PrefStore that is not persisted to disk. All preferences
-  // that store information about the browsing history or behavior of the user
-  // should have this property.
-  virtual bool ShallBeStoredInOverlay(const std::string& key) const;
+  // an in-memory PrefStore that is not persisted to disk.
+  bool ShallBeStoredInOverlay(const std::string& key) const;
 
   ObserverList<PrefStore::Observer, true> observers_;
   PrefValueMap overlay_;
   scoped_refptr<PersistentPrefStore> underlay_;
+  NamesMap overlay_to_underlay_names_map_;
+  NamesMap underlay_to_overlay_names_map_;
 
-  DISALLOW_COPY_AND_ASSIGN(IncognitoUserPrefStore);
+  DISALLOW_COPY_AND_ASSIGN(OverlayUserPrefStore);
 };
 
-#endif  // CHROME_BROWSER_PREFS_INCOGNITO_USER_PREF_STORE_H_
+#endif  // CHROME_BROWSER_PREFS_OVERLAY_USER_PREF_STORE_H_