ash: Drop the immediately following power button released induced forcing off request

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 b99148efaab18721db5814830f3ef9200d35a7c5..2a90377683139507dcb7065204c87c549c3f606f 100644
--- a/ash/system/chromeos/power/tablet_power_button_controller.h
+++ b/ash/system/chromeos/power/tablet_power_button_controller.h
@@ -117,6 +117,9 @@ class ASH_EXPORT TabletPowerButtonController
   // updated in SuspendDone().
   base::TimeTicks last_resume_time_;
 
+  // Saves the most recent timestamp that power button is released.
+  base::TimeTicks last_button_up_time_;
+
   // True if power button released should force off display.
   bool force_off_on_button_up_;