Enabled/disable touch screen in TabletPowerButtonController

ash/system/chromeos/power/tablet_power_button_controller.h

Index: ash/system/chromeos/power/tablet_power_button_controller.h
diff --git a/ash/system/chromeos/power/tablet_power_button_controller.h b/ash/system/chromeos/power/tablet_power_button_controller.h
index 66a5b61de06058e5b0529b0648b2e59d9cf1563d..46df12c052412017d35f0d5094e9f5fd6bb11d61 100644
--- a/ash/system/chromeos/power/tablet_power_button_controller.h
+++ b/ash/system/chromeos/power/tablet_power_button_controller.h
@@ -8,6 +8,7 @@
 #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"
@@ -25,6 +26,7 @@ class LockStateController;
 // instantiated and used in PowerButtonController.
 class ASH_EXPORT TabletPowerButtonController
     : public chromeos::PowerManagerClient::Observer,
+      public ShellObserver,
       public ui::EventHandler,
       public ui::InputDeviceEventObserver {
  public:
@@ -61,6 +63,9 @@ class ASH_EXPORT TabletPowerButtonController
   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;
@@ -72,8 +77,9 @@ class ASH_EXPORT TabletPowerButtonController
   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.