chromeos: Make ash system tray directly observe IME state changes

ash/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/features.gni")
 import("//build/config/ui.gni")
 import("//testing/test.gni")
 import("//ui/base/ui_features.gni")
 
 # Historical note: Ash shipped on Windows for a couple years to support
@@ skipping 357 matching lines @@
     "system/devicetype_utils.h",
     "system/display_scale/scale_detailed_view.cc",
     "system/display_scale/scale_detailed_view.h",
     "system/display_scale/scale_view.cc",
     "system/display_scale/scale_view.h",
     "system/display_scale/tray_scale.cc",
     "system/display_scale/tray_scale.h",
     "system/enterprise/enterprise_domain_observer.h",
     "system/enterprise/tray_enterprise.cc",
     "system/enterprise/tray_enterprise.h",
-    "system/ime/ime_observer.h",
     "system/ime/ime_util.cc",
     "system/ime/ime_util.h",
     "system/ime/tray_ime_chromeos.cc",
     "system/ime/tray_ime_chromeos.h",
     "system/ime_menu/ime_list_view.cc",
     "system/ime_menu/ime_list_view.h",
     "system/ime_menu/ime_menu_tray.cc",
     "system/ime_menu/ime_menu_tray.h",
     "system/keyboard_brightness_control_delegate.h",
     "system/keyboard_brightness_controller.cc",
@@ skipping 1139 matching lines @@
     "//content/public/app:both",
     "//device/bluetooth",
   ]
 
   data_deps = [
     "//ash/strings:ash_test_strings",
     "//ash/resources:ash_test_resources_with_content_100_percent",
     "//ash/resources:ash_test_resources_200_percent",
   ]
 }