Enable download page action for error page

chrome/renderer/net/net_error_helper.h

 // Copyright (c) 2013 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_RENDERER_NET_NET_ERROR_HELPER_H_
 #define CHROME_RENDERER_NET_NET_ERROR_HELPER_H_
 
 #include <memory>
 #include <string>
 
@@ skipping 94 matching lines @@
   void FetchNavigationCorrections(
       const GURL& navigation_correction_url,
       const std::string& navigation_correction_request_body) override;
   void CancelFetchNavigationCorrections() override;
   void SendTrackingRequest(const GURL& tracking_url,
                            const std::string& tracking_request_body) override;
   void ReloadPage(bool bypass_cache) override;
   void LoadPageFromCache(const GURL& page_url) override;
   void DiagnoseError(const GURL& page_url) override;
   void DownloadPageLater() override;
+  void SetIsShowingDownloadButton(bool show) override;
 
   void OnNetErrorInfo(int status);
   void OnSetNavigationCorrectionInfo(const GURL& navigation_correction_url,
                                      const std::string& language,
                                      const std::string& country_code,
                                      const std::string& api_key,
                                      const GURL& search_url);
 
   void OnNavigationCorrectionsFetched(const blink::WebURLResponse& response,
                                       const std::string& data);
@@ skipping 19 matching lines @@
   // Weak factory for vending a weak pointer to a NetErrorPageController. Weak
   // pointers are invalidated on each commit, to prevent getting messages from
   // Controllers used for the previous commit that haven't yet been cleaned up.
   base::WeakPtrFactory<NetErrorPageController::Delegate>
       weak_controller_delegate_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(NetErrorHelper);
 };
 
 #endif  // CHROME_RENDERER_NET_NET_ERROR_HELPER_H_