// Copyright 2017 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef COMPONENTS_UKM_OBSERVERS_HISTORY_DELETE_OBSERVER_H_
#define COMPONENTS_UKM_OBSERVERS_HISTORY_DELETE_OBSERVER_H_

#include "base/scoped_multi_source_observation.h"
#include "components/history/core/browser/history_service.h"
#include "components/history/core/browser/history_service_observer.h"

namespace ukm {

// Observes multiple HistoryService objects for any events that delete history.
// Handles cleanup and removing observers as objects are destroyed.
class HistoryDeleteObserver : public history::HistoryServiceObserver {
 public:
  HistoryDeleteObserver();

  HistoryDeleteObserver(const HistoryDeleteObserver&) = delete;
  HistoryDeleteObserver& operator=(const HistoryDeleteObserver&) = delete;

  ~HistoryDeleteObserver() override;

  // Starts observing a service for history deletions.
  void ObserveServiceForDeletions(history::HistoryService* history_service);

  // history::HistoryServiceObserver
  void OnHistoryDeletions(history::HistoryService* history_service,
                          const history::DeletionInfo& deletion_info) override;
  void HistoryServiceBeingDeleted(
      history::HistoryService* history_service) override;

 protected:
  virtual void OnHistoryDeleted() = 0;

 private:
  // Tracks observed history services, for cleanup.
  base::ScopedMultiSourceObservation<history::HistoryService,
                                     history::HistoryServiceObserver>
      history_observations_{this};
};

}  // namespace ukm

#endif  // COMPONENTS_UKM_OBSERVERS_HISTORY_DELETE_OBSERVER_H_