cros: Use custom icon for low-power charger notification

ash/system/chromeos/power/tray_power.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_SYSTEM_CHROMEOS_POWER_TRAY_POWER_H_
 #define ASH_SYSTEM_CHROMEOS_POWER_TRAY_POWER_H_
 
 #include "ash/system/tray/system_tray_item.h"
 #include "chromeos/power/power_manager_handler.h"
 
@@ skipping 57 matching lines @@
   // |supply_status|.
   static int GetBatteryImageOffset(
       const chromeos::PowerSupplyStatus& supply_status);
 
   // Looks up the actual icon in the icon array image for |image_index|.
   static gfx::ImageSkia GetBatteryImage(int image_index,
                                         int image_offset,
                                         bool charging_unreliable,
                                         IconSet icon_set);
 
-  // Returns an icon for the USB charger notification.
-  static gfx::Image GetUsbChargerNotificationImage();
-
   // Gets the battery accessible string for |supply_status|.
   static base::string16 GetAccessibleNameString(
       const chromeos::PowerSupplyStatus& supply_status);
 
   // Gets rounded battery percentage for |battery_percentage|.
   static int GetRoundedBatteryPercentage(double battery_percentage);
 
  private:
   friend class TrayPowerTest;
 
@@ skipping 36 matching lines @@
   // Power supply status at the last update.
   chromeos::PowerSupplyStatus last_power_supply_status_;
 
   DISALLOW_COPY_AND_ASSIGN(TrayPower);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_CHROMEOS_POWER_TRAY_POWER_H_