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// Copyright 2017 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 CHROME_BROWSER_FEATURE_ENGAGEMENT_SESSION_DURATION_UPDATER_H_
#define CHROME_BROWSER_FEATURE_ENGAGEMENT_SESSION_DURATION_UPDATER_H_
#include <memory>
#include "base/scoped_observer.h"
#include "base/timer/elapsed_timer.h"
#include "chrome/browser/metrics/desktop_session_duration/desktop_session_duration_tracker.h"
#include "components/keyed_service/core/keyed_service.h"
#include "components/prefs/pref_service.h"
namespace user_prefs {
class PrefRegistrySyncable;
} // namespace user_prefs
namespace feature_engagement {
// The SessionDurationUpdater tracks the total amount of observed time across
// Chrome restarts. Observed time in this context is active session time that
// occurs while there is a FeatureTracker whose active session time requirement
// has not been satisfied. This allows subclasses of FeatureTracker to check how
// much active time has passed, and decide whether to show their respective
// promos accordingly.
//
// When an active session is closed, DesktopSessionDurationTracker calls
// OnSessionEnded and the observed time is incremented and persisted. Then,
// OnSessionEnded is called on all of Features observing SessionDurationUpdater.
// If the feature has its time limit exceeded, it should remove itself as an
// observer of SessionDurationUpdater. If SessionDurationUpdater has no
// observers, it means that the time limits of all the observing features has
// been exceeded, so the SessionDurationUpdater removes itself as an observer of
// DesktopSessionDurationTracker and stops updating observed session time.
//
// If all observers are removed, SessionDurationUpdater doesn't continue
// updating the observed session time. However, if another feature is added as
// an observer later, SessionDurationUpdater starts incrementing the observed
// session time again.
class SessionDurationUpdater
: public metrics::DesktopSessionDurationTracker::Observer,
public KeyedService {
public:
// The methods for the observer will be called on the UI thread.
class Observer {
public:
virtual ~Observer() = default;
virtual void OnSessionEnded(base::TimeDelta total_session_time) = 0;
};
explicit SessionDurationUpdater(PrefService* pref_service,
const char* observed_session_time_pref_key);
~SessionDurationUpdater() override;
static void RegisterProfilePrefs(user_prefs::PrefRegistrySyncable* registry);
// Returns the total amount of observed active session time of the current
// session plus the previously recorded observed session time. The resulting
// value should be cumulative session time across all Chrome restarts.
base::TimeDelta GetCumulativeElapsedSessionTime();
// Gets the recorded observed session time which is cumulative for all
// previous sessions.
base::TimeDelta GetRecordedObservedSessionTime();
// For observing the status of the session tracker.
void AddObserver(Observer* observer);
void RemoveObserver(Observer* observer);
// metrics::DesktopSessionDurationtracker::Observer:
void OnSessionStarted(base::TimeTicks delta) override;
void OnSessionEnded(base::TimeDelta delta) override;
private:
// Adds the DesktopSessionDurationTracker observer.
void AddDurationTrackerObserver();
// Removes the DesktopSessionDurationTracker observer.
void RemoveDurationTrackerObserver();
// Returns the pref service associated with this SessionDurationUpdater.
virtual PrefService* GetPrefs();
// Observes the DesktopSessionDurationTracker and notifies when a desktop
// session starts and ends.
ScopedObserver<metrics::DesktopSessionDurationTracker,
metrics::DesktopSessionDurationTracker::Observer>
duration_tracker_observer_;
// Owned by Profile manager.
PrefService* const pref_service_;
// The profile dict key of kObservedSessionTime that tracks the observed
// session time for an In-Product Help feature.
const char* observed_session_time_dict_key_;
// Tracks the elapsed active session time while the browser is open.
std::unique_ptr<base::ElapsedTimer> current_session_timer_;
base::ObserverList<Observer> observer_list_;
DISALLOW_COPY_AND_ASSIGN(SessionDurationUpdater);
};
} // namespace feature_engagement
#endif // CHROME_BROWSER_FEATURE_ENGAGEMENT_SESSION_DURATION_UPDATER_H_