[New Tab Page] Change the mechanism to intercept online NTP errors

chrome/browser/ui/search/new_tab_page_interceptor_service.h

+// Copyright 2015 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 CHROME_BROWSER_UI_SEARCH_NEW_TAB_PAGE_INTERCEPTOR_SERVICE_H_
+#define CHROME_BROWSER_UI_SEARCH_NEW_TAB_PAGE_INTERCEPTOR_SERVICE_H_
+
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
+#include "components/keyed_service/core/keyed_service.h"
+#include "components/search_engines/template_url_service_observer.h"
+
+class NewTabPageInterceptor;
+class Profile;
+class TemplateURLService;
+
+namespace net {
+class URLRequestInterceptor;
+}
+
+// Owns a NewTabPageInterceptor.
+class NewTabPageInterceptorService : public KeyedService,
+                                     public TemplateURLServiceObserver {
+ public:
+  explicit NewTabPageInterceptorService(Profile* profile);
+  ~NewTabPageInterceptorService() override;
+
+  // TemplateURLServiceObserver override.
+  void OnTemplateURLServiceChanged() override;
+
+  scoped_ptr<net::URLRequestInterceptor> CreateInterceptor();
+
+ private:
+  Profile* profile_;
+  base::WeakPtr<NewTabPageInterceptor> interceptor_;
+  // The TemplateURLService that we are observing. It will outlive this
+  // NewTabPageInterceptorService due to the dependency declared in
+  // NewTabPageInterceptorServiceFactory.
+  TemplateURLService* template_url_service_;
+
+  DISALLOW_COPY_AND_ASSIGN(NewTabPageInterceptorService);
+};
+
+#endif  // CHROME_BROWSER_UI_SEARCH_NEW_TAB_PAGE_INTERCEPTOR_SERVICE_H_