[merge to m58] cros: Update touchscreen status with backlights forced off state during start

ash/wm/power_button_controller.cc

Index: ash/wm/power_button_controller.cc
diff --git a/ash/wm/power_button_controller.cc b/ash/wm/power_button_controller.cc
index 104d612dd7877cead0d573f7c6cd46fcc22d069e..3eee089db1ee80da2e2f6514da794b3092d2d02a 100644
--- a/ash/wm/power_button_controller.cc
+++ b/ash/wm/power_button_controller.cc
@@ -197,4 +197,9 @@ void PowerButtonController::PowerButtonEventReceived(
   OnPowerButtonEvent(down, timestamp);
 }
 
+void PowerButtonController::ResetTabletPowerButtonControllerForTest() {
+  tablet_controller_.reset(
+      new TabletPowerButtonController(lock_state_controller_));
+}
+
 }  // namespace ash