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

content/browser/webui/network_error_url_loader.h

Index: content/browser/webui/network_error_url_loader.h
diff --git a/content/browser/webui/network_error_url_loader.h b/content/browser/webui/network_error_url_loader.h
new file mode 100644
index 0000000000000000000000000000000000000000..076a66828600ce70fb26db06c81d536446a36b65
--- /dev/null
+++ b/content/browser/webui/network_error_url_loader.h
@@ -0,0 +1,18 @@
+// Copyright 2017 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.
+
+#ifndef CONTENT_BROWSER_WEBUI_NETWORK_ERROR_URL_LOADER_H_
+#define CONTENT_BROWSER_WEBUI_NETWORK_ERROR_URL_LOADER_H_
+
+#include "content/common/url_loader.mojom.h"
+
+namespace content {
+
+// Creates the data for chrome://network-error.
+void StartNetworkErrorsURLLoader(const ResourceRequest& request,
+                                 mojom::URLLoaderClientPtr client);
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_WEBUI_NETWORK_ERROR_URL_LOADER_H_