Move ChromeRequirementsChecker to //extensions as a PreloadCheck

extensions/common/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("//extensions/features/features.gni")
 import("//mojo/public/tools/bindings/mojom.gni")
 
 source_set("common_constants") {
   sources = [
@@ skipping 162 matching lines @@
       "manifest_handlers/mime_types_handler.cc",
       "manifest_handlers/mime_types_handler.h",
       "manifest_handlers/oauth2_manifest_handler.cc",
       "manifest_handlers/oauth2_manifest_handler.h",
       "manifest_handlers/offline_enabled_info.cc",
       "manifest_handlers/offline_enabled_info.h",
       "manifest_handlers/options_page_info.cc",
       "manifest_handlers/options_page_info.h",
       "manifest_handlers/permissions_parser.cc",
       "manifest_handlers/permissions_parser.h",
+      "manifest_handlers/plugins_handler.cc",
+      "manifest_handlers/plugins_handler.h",
       "manifest_handlers/requirements_info.cc",
       "manifest_handlers/requirements_info.h",
       "manifest_handlers/sandboxed_page_info.cc",
       "manifest_handlers/sandboxed_page_info.h",
       "manifest_handlers/shared_module_info.cc",
       "manifest_handlers/shared_module_info.h",
       "manifest_handlers/web_accessible_resources_info.cc",
       "manifest_handlers/web_accessible_resources_info.h",
       "manifest_handlers/webview_info.cc",
       "manifest_handlers/webview_info.h",
@@ skipping 189 matching lines @@
       "//ui/base",
       "//ui/gfx",
       "//url",
     ]
 
     if (is_chromeos) {
       sources += [ "manifest_handlers/action_handlers_handler_unittest.cc" ]
     }
   }
 }  # enable_extensions