Introduce a new framework for back-and-forth tracked/protected preferences migration.

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/callback.h"
 #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.
@@ skipping 13 matching lines @@
   // 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,
-      const base::Closure& on_initialization);
+      const std::set<std::string>& selected_pref_names);
 
   // PrefStore implementation
   virtual void AddObserver(Observer* observer) OVERRIDE;
   virtual void RemoveObserver(Observer* observer) OVERRIDE;
   virtual bool HasObservers() const OVERRIDE;
   virtual bool IsInitializationComplete() const OVERRIDE;
   virtual bool GetValue(const std::string& key,
                         const base::Value** result) const OVERRIDE;
 
   // WriteablePrefStore implementation
@@ skipping 26 matching lines @@
    private:
     SegregatedPrefStore* outer_;
     int failed_sub_initializations_;
     int successful_sub_initializations_;
 
     DISALLOW_COPY_AND_ASSIGN(AggregatingObserver);
   };
 
   virtual ~SegregatedPrefStore();
 
-  // Returns |selected_pref_store| if |key| is selected or a value is present
-  // in |selected_pref_store|. This could happen if |key| was previously
-  // selected.
+  // 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;
 
-  // Returns |selected_pref_store| if |key| is selected. If |key| is
-  // unselected but has a value in |selected_pref_store|, moves the value to
-  // |default_pref_store| before returning |default_pref_store|.
-  PersistentPrefStore* StoreForKey(const std::string& key);
-
   scoped_refptr<PersistentPrefStore> default_pref_store_;
   scoped_refptr<PersistentPrefStore> selected_pref_store_;
   std::set<std::string> selected_preference_names_;
-  base::Closure on_initialization_;
 
   scoped_ptr<PersistentPrefStore::ReadErrorDelegate> read_error_delegate_;
   ObserverList<PrefStore::Observer, true> observers_;
   AggregatingObserver aggregating_observer_;
 
   DISALLOW_COPY_AND_ASSIGN(SegregatedPrefStore);
 };
 
 #endif  // CHROME_BROWSER_PREFS_TRACKED_SEGREGATED_PREF_STORE_H_