Add support for subresource request fallback in AppCache for the network service..

content/browser/appcache/appcache_url_request.h

 // Copyright (c) 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_APPCACHE_APPCACHE_URL_REQUEST_H_
 #define CONTENT_BROWSER_APPCACHE_APPCACHE_URL_REQUEST_H_
 
 #include "content/browser/appcache/appcache_request.h"
 #include "content/common/content_export.h"
 
@@ skipping 15 matching lines @@
   // AppCacheRequest overrides.
   const GURL& GetURL() const override;
   const std::string& GetMethod() const override;
   const GURL& GetFirstPartyForCookies() const override;
   const GURL GetReferrer() const override;
   bool IsSuccess() const override;
   bool IsCancelled() const override;
   bool IsError() const override;
   int GetResponseCode() const override;
   std::string GetResponseHeaderByName(const std::string& name) const override;
-
   net::URLRequest* GetURLRequest() override;
+  AppCacheURLRequest* AsURLRequest() override;
 
  protected:
   explicit AppCacheURLRequest(net::URLRequest* url_request);
 
  private:
   net::URLRequest* url_request_;
 
   DISALLOW_COPY_AND_ASSIGN(AppCacheURLRequest);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_APPCACHE_APPCACHE_REQUEST_H_