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// Copyright 2014 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_METRICS_CLEAN_EXIT_BEACON_H_
#define COMPONENTS_METRICS_CLEAN_EXIT_BEACON_H_
#include "base/macros.h"
#include "base/strings/string16.h"
#include "base/time/time.h"
class PrefRegistrySimple;
class PrefService;
namespace metrics {
// Reads and updates a beacon used to detect whether the previous browser
// process exited cleanly.
class CleanExitBeacon {
public:
// Instantiates a CleanExitBeacon whose value is stored in |local_state|.
// |local_state| must be fully initialized.
// On Windows, |backup_registry_key| is used to store a backup of the beacon.
// It is ignored on other platforms.
CleanExitBeacon(
const base::string16& backup_registry_key,
PrefService* local_state);
~CleanExitBeacon();
// Returns the original value of the beacon.
bool exited_cleanly() const { return initial_value_; }
// Returns the original value of the last live timestamp.
base::Time browser_last_live_timestamp() const {
return initial_browser_last_live_timestamp_;
}
// Writes the provided beacon value and updates the last live timestamp.
void WriteBeaconValue(bool exited_cleanly);
// Updates the last live timestamp.
void UpdateLastLiveTimestamp();
// Registers local state prefs used by this class.
static void RegisterPrefs(PrefRegistrySimple* registry);
private:
PrefService* const local_state_;
const bool initial_value_;
// This is the value of the last live timestamp from local state at the
// time of construction. It notes a timestamp from the previous browser
// session when the browser was known to be alive.
const base::Time initial_browser_last_live_timestamp_;
const base::string16 backup_registry_key_;
DISALLOW_COPY_AND_ASSIGN(CleanExitBeacon);
};
} // namespace metrics
#endif // COMPONENTS_METRICS_CLEAN_EXIT_BEACON_H_
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