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..2c332cb3f7a3f9aac1824a2a68d21176012a48c6 100644
--- a/content/browser/appcache/appcache_request_handler.h
+++ b/content/browser/appcache/appcache_request_handler.h
@@ -165,6 +165,13 @@ class CONTENT_EXPORT AppCacheRequestHandler
                          ResourceContext* resource_context,
                          LoaderCallback callback) override;
   mojom::URLLoaderFactoryPtr MaybeCreateSubresourceFactory() override;
+  bool MaybeGetFallbackForResponse(const ResourceResponseHead& response,
+                                   mojom::URLLoaderClientPtr* client,
+                                   mojom::URLLoaderRequest* request) override;
+  bool MaybeGetFallbackForRedirect(const ResourceResponseHead& response,
+                                   const net::RedirectInfo& redirect_info,
+                                   mojom::URLLoaderClientPtr* client,
+                                   mojom::URLLoaderRequest* request) override;
 
   // Data members -----------------------------------------------