Add support for fallback content for the frame. This includes main and subframes.

content/browser/appcache/appcache_request_handler.h

Index: content/browser/appcache/appcache_request_handler.h
diff --git a/content/browser/appcache/appcache_request_handler.h b/content/browser/appcache/appcache_request_handler.h
index 24ee0fcc7456cbd50af6d75a4c43e522325a6630..3c1b260c7524c7c9b5e32617bcea4af4fda13198 100644
--- a/content/browser/appcache/appcache_request_handler.h
+++ b/content/browser/appcache/appcache_request_handler.h
@@ -165,6 +165,10 @@ class CONTENT_EXPORT AppCacheRequestHandler
                          ResourceContext* resource_context,
                          LoaderCallback callback) override;
   mojom::URLLoaderFactoryPtr MaybeCreateSubresourceFactory() override;
+  bool MaybeCreateLoaderForResponse(
+      const ResourceResponseHead& response,
+      mojom::URLLoaderPtr* loader,
+      mojom::URLLoaderClientRequest* client_request) override;
 
   // Data members -----------------------------------------------
 
@@ -235,8 +239,7 @@ class CONTENT_EXPORT AppCacheRequestHandler
   // the AppCache, we delete the job.
   std::unique_ptr<AppCacheJob> navigation_request_job_;
 
-  // In the network service world, points to the getter for the network URL
-  // loader.
+  // Points to the getter for the network URL loader.
   scoped_refptr<URLLoaderFactoryGetter> network_url_loader_factory_getter_;
 
   friend class content::AppCacheRequestHandlerTest;