ash/display/privacy_screen_controller.h

// Copyright 2020 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 ASH_DISPLAY_PRIVACY_SCREEN_CONTROLLER_H_
#define ASH_DISPLAY_PRIVACY_SCREEN_CONTROLLER_H_

#include <memory>

#include "ash/ash_export.h"
#include "ash/public/cpp/session/session_observer.h"
#include "base/observer_list.h"
#include "ui/display/manager/display_configurator.h"

class PrefRegistrySimple;
class PrefService;
class PrefChangeRegistrar;

namespace ash {

// Controls the privacy screen feature.
class ASH_EXPORT PrivacyScreenController
    : public SessionObserver,
      display::DisplayConfigurator::Observer {
 public:
  class Observer : public base::CheckedObserver {
   public:
    // Called when the privacy screen setting is changed.
    virtual void OnPrivacyScreenSettingChanged(bool enabled) {}

   protected:
    ~Observer() override = default;
  };

  PrivacyScreenController();
  ~PrivacyScreenController() override;

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

  static void RegisterProfilePrefs(PrefRegistrySimple* registry);

  // Whether or not the privacy screen feature is supported by the device.
  bool IsSupported() const;
  // Whether or not the privacy screen feature is enforced by policy.
  bool IsManaged() const;
  // Get the PrivacyScreen settings stored in the current active user prefs.
  bool GetEnabled() const;
  // Set the desired PrivacyScreen settings in the current active user prefs.
  void SetEnabled(bool enabled);

  void AddObserver(Observer* observer);
  void RemoveObserver(Observer* observer);

  // SessionObserver:
  void OnActiveUserPrefServiceChanged(PrefService* pref_service) override;
  void OnSigninScreenPrefServiceInitialized(PrefService* pref_service) override;

  // DisplayConfigurator::Observer:
  void OnDisplayModeChanged(
      const std::vector<display::DisplaySnapshot*>& displays) override;

 private:
  // Called when the user pref for the status of PrivacyScreen is changed.
  void OnEnabledPrefChanged(bool notify_observers);

  // Called when a change to |active_user_pref_service_| is detected (i.e. when
  // OnActiveUserPrefServiceChanged() is called.
  void InitFromUserPrefs();

  // The pref service of the currently active user. Can be null in
  // ash_unittests.
  PrefService* active_user_pref_service_ = nullptr;

  // Set to true when entering the login screen. This should happen once per
  // Chrome restart.
  bool applying_login_screen_prefs_ = false;

  base::ObserverList<Observer> observers_;

  // The registrar used to watch privacy screen prefs changes in the above
  // |active_user_pref_service_| from outside ash.
  // NOTE: Prefs are how Chrome communicates changes to the
  // PrivacyScreenController settings controlled by this class from the WebUI
  // settings.
  std::unique_ptr<PrefChangeRegistrar> pref_change_registrar_;
};

}  // namespace ash

#endif  // ASH_DISPLAY_PRIVACY_SCREEN_CONTROLLER_H_