cros: Update touchscreen status with backlights forced off state during start

ash/wm/power_button_controller.h

 // Copyright (c) 2012 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_POWER_BUTTON_CONTROLLER_H_
 #define ASH_WM_POWER_BUTTON_CONTROLLER_H_
 
 #include <memory>
 
 #include "ash/ash_export.h"
@@ skipping 34 matching lines @@
   void OnKeyEvent(ui::KeyEvent* event) override;
 
   // Overriden from display::DisplayConfigurator::Observer:
   void OnDisplayModeChanged(
       const display::DisplayConfigurator::DisplayStateList& outputs) override;
 
   // Overridden from chromeos::PowerManagerClient::Observer:
   void PowerButtonEventReceived(bool down,
                                 const base::TimeTicks& timestamp) override;
 
+  void ResetTabletPowerButtonControllerForTest();

[Daniel Erat, 2017/05/03 03:59:37]

nit: document what this does, e.g.

// Resets |tablet_controller_| to hold a new object to simulate
// Chrome starting.

[Qiang(Joe) Xu, 2017/05/03 04:17:33]

Done.

+
   TabletPowerButtonController* tablet_power_button_controller_for_test() {
     return tablet_controller_.get();
   }
 
  private:
   // Are the power or lock buttons currently held?
   bool power_button_down_;
   bool lock_button_down_;
 
   // True when the volume down button is being held down.
@@ skipping 19 matching lines @@
 
   // Handles events for convertible/tablet devices.
   std::unique_ptr<TabletPowerButtonController> tablet_controller_;
 
   DISALLOW_COPY_AND_ASSIGN(PowerButtonController);
 };
 
 }  // namespace ash
 
 #endif  // ASH_WM_POWER_BUTTON_CONTROLLER_H_