Implement chrome://network-error with network service.

content/browser/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("//gpu/vulkan/features.gni")
 import("//media/media_options.gni")
 import("//ppapi/features/features.gni")
 import("//printing/features/features.gni")
@@ skipping 1490 matching lines @@
     "websockets/websocket_impl.cc",
     "websockets/websocket_impl.h",
     "websockets/websocket_manager.cc",
     "websockets/websocket_manager.h",
     "webui/content_web_ui_controller_factory.cc",
     "webui/content_web_ui_controller_factory.h",
     "webui/generic_handler.cc",
     "webui/generic_handler.h",
     "webui/i18n_source_stream.cc",
     "webui/i18n_source_stream.h",
+    "webui/network_error_url_loader.cc",
+    "webui/network_error_url_loader.h",
     "webui/shared_resources_data_source.cc",
     "webui/shared_resources_data_source.h",
     "webui/url_data_manager.cc",
     "webui/url_data_manager.h",
     "webui/url_data_manager_backend.cc",
     "webui/url_data_manager_backend.h",
     "webui/url_data_source_impl.cc",
     "webui/url_data_source_impl.h",
     "webui/web_ui_controller_factory_registry.cc",
     "webui/web_ui_controller_factory_registry.h",
@@ skipping 620 matching lines @@
   if (!is_component_build) {
     public_deps = [
       ":browser",
     ]
   } else {
     public_deps = [
       "//third_party/leveldatabase",
     ]
   }
 }