Take out and generalize user prefs overriding from IncognitoUserPrefStore.

chrome/browser/prefs/incognito_user_pref_store.h

Index: chrome/browser/prefs/incognito_user_pref_store.h
diff --git a/chrome/browser/prefs/incognito_user_pref_store.h b/chrome/browser/prefs/incognito_user_pref_store.h
index b5be17eb7c66b728feb9a24615738884c9bc1da0..40afbb5f7b5dabd2a15260955d6902f2bf4eb08f 100644
--- a/chrome/browser/prefs/incognito_user_pref_store.h
+++ b/chrome/browser/prefs/incognito_user_pref_store.h
@@ -8,62 +8,13 @@
 
 #include <string>
 
-#include "base/basictypes.h"
-#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"
+#include "chrome/browser/prefs/overlay_user_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 IncognitoUserPrefStore : public OverlayUserPrefStore {
  public:
   explicit IncognitoUserPrefStore(PersistentPrefStore* underlay);
-  virtual ~IncognitoUserPrefStore();
-
-  // Returns true if a value has been set for the |key| in this
-  // IncognitoUserPrefStore, 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);
 
  private:
-  // Methods of PrefStore::Observer.
-  virtual void OnPrefValueChanged(const std::string& key);
-  virtual void OnInitializationCompleted(bool succeeded);
-
-  // 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;
-
-  ObserverList<PrefStore::Observer, true> observers_;
-  PrefValueMap overlay_;
-  scoped_refptr<PersistentPrefStore> underlay_;
 
   DISALLOW_COPY_AND_ASSIGN(IncognitoUserPrefStore);
 };