ash: Use system tray mojo interface to show system update tray icon

chrome/browser/ui/BUILD.gn

 # Copyright 2014 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.
 
 import("//build/config/chromecast_build.gni")
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//build/split_static_library.gni")
 import("//chrome/common/features.gni")
@@ skipping 1374 matching lines @@
       "ash/networking_config_delegate_chromeos.cc",
       "ash/networking_config_delegate_chromeos.h",
       "ash/palette_delegate_chromeos.cc",
       "ash/palette_delegate_chromeos.h",
       "ash/session_state_delegate_chromeos.cc",
       "ash/session_state_delegate_chromeos.h",
       "ash/session_util.cc",
       "ash/session_util.h",
       "ash/system_tray_delegate_chromeos.cc",
       "ash/system_tray_delegate_chromeos.h",
-      "ash/system_tray_delegate_utils.cc",
-      "ash/system_tray_delegate_utils.h",
       "ash/volume_controller.cc",
       "ash/volume_controller.h",
       "ash/vpn_list_forwarder.cc",
       "ash/vpn_list_forwarder.h",
       "views/ash/chrome_browser_main_extra_parts_ash.cc",
       "views/ash/chrome_browser_main_extra_parts_ash.h",
       "views/ash/tab_scrubber.cc",
       "views/ash/tab_scrubber.h",
       "views/touch_uma/touch_uma_ash.cc",
       "window_sizer/window_sizer_ash.cc",
@@ skipping 2074 matching lines @@
       "test/test_confirm_bubble_model.cc",
       "test/test_confirm_bubble_model.h",
     ]
     deps += [ "//chrome/test:test_support_ui" ]
   }
 
   if (enable_extensions) {
     deps += [ "//extensions/browser" ]
   }
 }