1// Copyright 2014 The Chromium Authors. All rights reserved. 2// Use of this source code is governed by a BSD-style license that can be 3// found in the LICENSE file. 4 5#ifndef COMPONENTS_METRICS_CLEAN_EXIT_BEACON_H_ 6#define COMPONENTS_METRICS_CLEAN_EXIT_BEACON_H_ 7 8#include "base/macros.h" 9#include "base/strings/string16.h" 10 11class PrefService; 12 13namespace metrics { 14 15// Reads and updates a beacon used to detect whether the previous browser 16// process exited cleanly. 17class CleanExitBeacon { 18 public: 19 // Instantiates a CleanExitBeacon whose value is stored in |local_state|. 20 // |local_state| must be fully initialized. 21 // On Windows, |backup_registry_key| is used to store a backup of the beacon. 22 // It is ignored on other platforms. 23 CleanExitBeacon( 24 const base::string16& backup_registry_key, 25 PrefService* local_state); 26 27 ~CleanExitBeacon(); 28 29 // Returns the original value of the beacon. 30 bool exited_cleanly() const { return initial_value_; } 31 32 // Writes the provided beacon value. 33 void WriteBeaconValue(bool exited_cleanly); 34 35 private: 36 PrefService* const local_state_; 37 const bool initial_value_; 38 const base::string16 backup_registry_key_; 39 40 DISALLOW_COPY_AND_ASSIGN(CleanExitBeacon); 41}; 42 43} // namespace metrics 44 45#endif // COMPONENTS_METRICS_CLEAN_EXIT_BEACON_H_ 46