Componentize PrefSyncableService and support classes.

chrome/browser/prefs/pref_model_associator_client.h

-// Copyright 2015 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_PREF_MODEL_ASSOCIATOR_CLIENT_H_
-#define CHROME_BROWSER_PREFS_PREF_MODEL_ASSOCIATOR_CLIENT_H_
-
-#include <string>
-
-#include "base/macros.h"
-
-// This class allows the embedder to configure the PrefModelAssociator to
-// have a different behaviour when receiving preference synchronisations
-// events from the server.
-class PrefModelAssociatorClient {
- public:
-  // Returns true if the preference named |pref_name| is a list preference
-  // whose server value is merged with local value during synchronisation.
-  virtual bool IsMergeableListPreference(
-      const std::string& pref_name) const = 0;
-
-  // Returns true if the preference named |pref_name| is a dictionary preference
-  // whose server value is merged with local value during synchronisation.
-  virtual bool IsMergeableDictionaryPreference(
-      const std::string& pref_name) const = 0;
-
-  // Returns true if the preference named |new_pref_name| is the new name for
-  // an old preference. The old name will be returned via |old_pref_name|.
-  virtual bool IsMigratedPreference(const std::string& new_pref_name,
-                                    std::string* old_pref_name) const = 0;
-
-  // Returns true if the preference named |old_pref_name| is the new name for
-  // a new preference. The old name will be returned via |new_pref_name|.
-  virtual bool IsOldMigratedPreference(const std::string& old_pref_name,
-                                       std::string* new_pref_name) const = 0;
-
- protected:
-  PrefModelAssociatorClient() {}
-  virtual ~PrefModelAssociatorClient() {}
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(PrefModelAssociatorClient);
-};
-
-#endif  // CHROME_BROWSER_PREFS_PREF_MODEL_ASSOCIATOR_CLIENT_H_