Upstream most of the iOS WebUI support in ios/web/

ios/web/webui/web_ui_ios_controller_factory_registry.h

+// 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.
+
+#ifndef IOS_WEB_WEBUI_WEB_UI_IOS_CONTROLLER_FACTORY_REGISTRY_H_
+#define IOS_WEB_WEBUI_WEB_UI_IOS_CONTROLLER_FACTORY_REGISTRY_H_
+
+#include "base/memory/singleton.h"
+#include "ios/public/provider/web/web_ui_ios_controller_factory.h"
+
+namespace web {
+
+// A singleton which holds on to all the registered WebUIIOSControllerFactory
+// instances.
+class WebUIIOSControllerFactoryRegistry : public WebUIIOSControllerFactory {
+ public:
+  static WebUIIOSControllerFactoryRegistry* GetInstance();
+
+  // WebUIIOSControllerFactory implementation. Each method loops through the
+  // same method on all the factories.
+  WebUIIOSController* CreateWebUIIOSControllerForURL(
+      WebUIIOS* web_ui,
+      const GURL& url) const override;
+
+ private:
+  friend struct DefaultSingletonTraits<WebUIIOSControllerFactoryRegistry>;
+
+  WebUIIOSControllerFactoryRegistry();
+  ~WebUIIOSControllerFactoryRegistry() override;
+
+  DISALLOW_COPY_AND_ASSIGN(WebUIIOSControllerFactoryRegistry);
+};
+
+}  // namespace web
+
+#endif  // IOS_WEB_WEBUI_WEB_UI_IOS_CONTROLLER_FACTORY_REGISTRY_H_