components/metrics/clean_exit_beacon.h

   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
  11 class PrefService;
  12
  13 namespace metrics {
  14
  15 // Reads and updates a beacon used to detect whether the previous browser
  16 // process exited cleanly.
  17 class 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_