Tablet-like power button behavior on Convertible/Tablet ChromeOS devices

ash/wm/tablet_power_button_controller.h

+// Copyright 2016 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_WM_TABLET_POWER_BUTTON_CONTROLLER_H_
+#define ASH_WM_TABLET_POWER_BUTTON_CONTROLLER_H_
+
+#include "ash/ash_export.h"
+#include "base/macros.h"
+#include "base/time/time.h"
+#include "base/timer/timer.h"
+#include "ui/events/event_handler.h"
+
+namespace ash {
+
+class LockStateController;
+
+// Handles power button events on convertible/tablet device. This class is
+// instantiated and used in PowerButtonController.
+class ASH_EXPORT TabletPowerButtonController : public ui::EventHandler {
+ public:
+  // Helper class used by tablet power button tests to access internal state.
+  class ASH_EXPORT TestApi {
+   public:
+    explicit TestApi(TabletPowerButtonController* controller);
+    virtual ~TestApi();
+
+    // Returns true when |tablet_power_button_timer_| is not timeout.
+    bool TabletPowerButtonTimerIsRunning() const;
+
+    // Emulates |tablet_power_button_timer_| timeout.
+    void TriggerTabletPowerButtonTimeout();
+
+   private:
+    TabletPowerButtonController* controller_;  // Not owned.
+
+    DISALLOW_COPY_AND_ASSIGN(TestApi);
+  };
+
+  explicit TabletPowerButtonController(LockStateController* controller);
+  ~TabletPowerButtonController() override;
+
+  // Returns true if power button events should be handled by this class instead
+  // of PowerButtonController.
+  bool ShouldHandlePowerButtonEvents() const;

[Qiang(Joe) Xu, 2016/11/04 23:18:21]

It is the same as "IsTabletModeSupported". Using ShouldHandlePowerButtonEvents
is to make it more clear?

+
+  void OnPowerButtonEvent(bool down,
+                          const base::TimeTicks& timestamp,
+                          bool brightness_is_zero);
+
+  // ui::EventHandler:
+  void OnKeyEvent(ui::KeyEvent* event) override;
+  void OnMouseEvent(ui::MouseEvent* event) override;
+
+ private:
+  // Set backlights to |forced_off| if needed.
+  void SetBacklightsForcedOff(bool forced_off);
+
+  // Sends a request to powerd to get the backlights forced off state so that
+  // |backlights_forced_off_| can be initialized.
+  void GetInitialBacklightsForcedOff();
+
+  // Initializes |backlights_forced_off_|.
+  void OnGotInitialBacklightsForcedOff(bool is_forced_off);
+
+  // Starts |tablet_power_button_timer_| when the power button is pressed while
+  // in tablet mode.
+  void StartTabletPowerButtonTimer();
+
+  // Called by |tablet_power_button_timer_| to start the pre-shutdown animation.
+  void OnTabletPowerButtonTimeout();
+
+  // Locks the screen if the "require password to wake from sleep" pref is set
+  // and locking is possible.
+  void LockScreenIfRequired();
+
+  // Returns true if device is a convertible/tablet device or has
+  // kAshEnableTouchViewTesting in test, otherwise false.
+  bool IsTabletModeSupported() const;
+
+  // Returns true if device is currently in tablet/maximize mode, otherwise
+  // false.
+  bool IsTabletModeActive() const;
+
+  // Current forced-off state of backlights.
+  bool backlights_forced_off_ = false;
+
+  // True if the screen was off when the power button was pressed.
+  bool power_button_down_while_screen_off_ = false;
+
+  // Started when the tablet power button is pressed and stopped when it's
+  // released. Runs OnTabletPowerButtonTimeout() to start shutdown.
+  base::OneShotTimer tablet_power_button_timer_;
+
+  LockStateController* controller_;  // Not owned.
+
+  DISALLOW_COPY_AND_ASSIGN(TabletPowerButtonController);
+};
+
+}  // namespace ash
+
+#endif  // ASH_WM_TABLET_POWER_BUTTON_CONTROLLER_H_