components/sync_preferences/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 COMPONENTS_SYNC_PREFERENCES_PREF_MODEL_ASSOCIATOR_CLIENT_H_
#define COMPONENTS_SYNC_PREFERENCES_PREF_MODEL_ASSOCIATOR_CLIENT_H_

#include <string>

#include "base/macros.h"
#include "base/values.h"

namespace sync_preferences {

// 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 the merged value if the client wants to apply a custom merging
  // strategy to the preference named |pref_name| with local value |local_value|
  // and server-provided value |server_value|. Otherwise, returns |nullptr| and
  // the server's value will be chosen.
  virtual std::unique_ptr<base::Value> MaybeMergePreferenceValues(
      const std::string& pref_name,
      const base::Value& local_value,
      const base::Value& server_value) const = 0;

 protected:
  PrefModelAssociatorClient() {}
  virtual ~PrefModelAssociatorClient() {}

 private:
  DISALLOW_COPY_AND_ASSIGN(PrefModelAssociatorClient);
};

}  // namespace sync_preferences

#endif  // COMPONENTS_SYNC_PREFERENCES_PREF_MODEL_ASSOCIATOR_CLIENT_H_