Enabled/disable touch screen in TabletPowerButtonController

ash/system/chromeos/power/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_SYSTEM_CHROMEOS_POWER_TABLET_POWER_BUTTON_CONTROLLER_H_
 #define ASH_SYSTEM_CHROMEOS_POWER_TABLET_POWER_BUTTON_CONTROLLER_H_
 
 #include <memory>
 
 #include "ash/ash_export.h"
+#include "ash/common/shell_observer.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/time/tick_clock.h"
 #include "base/time/time.h"
 #include "base/timer/timer.h"
 #include "chromeos/dbus/power_manager_client.h"
 #include "ui/events/devices/input_device_event_observer.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 chromeos::PowerManagerClient::Observer,
+      public ShellObserver,
       public ui::EventHandler,
       public ui::InputDeviceEventObserver {
  public:
   // Helper class used by tablet power button tests to access internal state.
   class ASH_EXPORT TestApi {
    public:
     explicit TestApi(TabletPowerButtonController* controller);
     ~TestApi();
 
     // Returns true when |shutdown_timer_| is running.
@@ skipping 16 matching lines @@
   bool ShouldHandlePowerButtonEvents() const;
 
   // Handles a power button event.
   void OnPowerButtonEvent(bool down, const base::TimeTicks& timestamp);
 
   // Overridden from chromeos::PowerManagerClient::Observer:
   void PowerManagerRestarted() override;
   void BrightnessChanged(int level, bool user_initiated) override;
   void SuspendDone(const base::TimeDelta& sleep_duration) override;
 
+  // Overridden from ShellObserver:
+  void OnLoginStateChanged(LoginStatus status) override;

[Qiang(Joe) Xu, 2016/11/30 22:09:11]

This change is to fix the bug for this:
On user logged in state, SetBacklightsForcedOff by pressing power button.
Touchscreen is disabled and saved to the prefs; backlights are forced off and
managed by powerd.

Now deploy_chrome, and when finished, click the touchpad to stop the backlights
forced off. However, since now no user is logged in, touchscreen enabled is not
saved to the previous prefs, but saved to the offtherecord-profile. When user is
logged in, touchscreen is still disabled.

Solution here is when OnLoginStateChanged is called, making a sync call to sync
the touchscreen state with backlights state.

+
   // Overridden from ui::EventHandler:
   void OnKeyEvent(ui::KeyEvent* event) override;
   void OnMouseEvent(ui::MouseEvent* event) override;
 
   // Overridden from ui::InputDeviceObserver:
   void OnStylusStateChanged(ui::StylusState state) override;
 
   // Overrides the tick clock used by |this| for testing.
   void SetTickClockForTesting(std::unique_ptr<base::TickClock> tick_clock);
 
  private:
-  // Set backlights to |forced_off| if they aren't already.
-  void SetBacklightsForcedOff(bool forced_off);
+  // Set backlights to |forced_off| and the corresponding enabled state of
+  // touchscreen if they aren't already.
+  void SetDisplayForcedOff(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 |shutdown_timer_| when the power button is pressed while in
   // tablet mode.
@@ skipping 29 matching lines @@
   LockStateController* controller_;  // Not owned.
 
   base::WeakPtrFactory<TabletPowerButtonController> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(TabletPowerButtonController);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_CHROMEOS_POWER_TABLET_POWER_BUTTON_CONTROLLER_H_