Vectorize power icon in Ash system menu for MD

ash/resources/vector_icons/BUILD.gn

 # Copyright 2016 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.
 
 action("aggregate_vector_icons") {
   visibility = [ ":*" ]
 
   script = "//ui/gfx/vector_icons/aggregate_vector_icons.py"
 
   icons = [
@@ skipping 32 matching lines @@
     "system_menu_caps_lock.1x.icon",
     "system_menu_caps_lock.icon",
     "system_menu_cast.1x.icon",
     "system_menu_cast.icon",
     "system_menu_child_user.1x.icon",
     "system_menu_child_user.icon",
     "system_menu_help.1x.icon",
     "system_menu_help.icon",
     "system_menu_keyboard.1x.icon",
     "system_menu_keyboard.icon",
+    "system_menu_power.1x.icon",
+    "system_menu_power.icon",
     "system_menu_rotation_lock_auto.1x.icon",
     "system_menu_rotation_lock_auto.icon",
     "system_menu_rotation_lock_locked.1x.icon",
     "system_menu_rotation_lock_locked.icon",
     "system_menu_screen_share.1x.icon",
     "system_menu_screen_share.icon",
     "system_menu_sms.icon",
     "system_menu_supervised_user.1x.icon",
     "system_menu_supervised_user.icon",
     "system_menu_timer.1x.icon",
@@ skipping 52 matching lines @@
 source_set("vector_icons") {
   sources = get_target_outputs(":aggregate_vector_icons")
   sources += [ "//ui/gfx/vector_icon_types.h" ]
 
   deps = [
     ":aggregate_vector_icons",
     "//base",
     "//skia",
   ]
 }