Replace ExtensionInstallChecker with generic PreloadCheckGroup

chrome/browser/extensions/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("//chrome/common/features.gni")
 import("//extensions/features/features.gni")
 import("//media/media_options.gni")
 import("//rlz/features/features.gni")
@@ skipping 563 matching lines @@
     "extension_garbage_collector.cc",
     "extension_garbage_collector.h",
     "extension_garbage_collector_chromeos.cc",
     "extension_garbage_collector_chromeos.h",
     "extension_garbage_collector_factory.cc",
     "extension_garbage_collector_factory.h",
     "extension_gcm_app_handler.cc",
     "extension_gcm_app_handler.h",
     "extension_icon_manager.cc",
     "extension_icon_manager.h",
-    "extension_install_checker.cc",
-    "extension_install_checker.h",
     "extension_install_error_menu_item_id_provider.cc",
     "extension_install_error_menu_item_id_provider.h",
     "extension_install_prompt.cc",
     "extension_install_prompt.h",
     "extension_install_prompt_show_params.cc",
     "extension_install_prompt_show_params.h",
     "extension_install_ui_util.cc",
     "extension_install_ui_util.h",
     "extension_keybinding_registry.cc",
     "extension_keybinding_registry.h",
@@ skipping 592 matching lines @@
       "api/braille_display_private/brlapi_connection.cc",
       "api/braille_display_private/brlapi_connection.h",
       "api/braille_display_private/brlapi_keycode_map.cc",
       "api/braille_display_private/brlapi_keycode_map.h",
     ]
     deps += [ "//build/linux/libbrlapi" ]
   } else {
     sources += [ "api/braille_display_private/braille_controller_stub.cc" ]
   }
 }