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

content/browser/appcache/appcache_url_loader_job.h

Index: content/browser/appcache/appcache_url_loader_job.h
diff --git a/content/browser/appcache/appcache_url_loader_job.h b/content/browser/appcache/appcache_url_loader_job.h
index d7ea502709cfebbcc07536d13c23b72f4c0cdc1b..0ee7867a3eba8746f4a0d15a9767829ca7fc5dd5 100644
--- a/content/browser/appcache/appcache_url_loader_job.h
+++ b/content/browser/appcache/appcache_url_loader_job.h
@@ -112,6 +112,11 @@ class CONTENT_EXPORT AppCacheURLLoaderJob : public AppCacheJob,
     sub_resource_handler_ = std::move(handler);
   }
 
+  // Binds to the URLLoaderClient instance passed in via the |client|
+  // parameter.
+  void BindToClient(mojom::URLLoaderClientPtr client,
+                    mojom::URLLoaderRequest request);
+
  protected:
   // AppCacheJob::Create() creates this instance.
   friend class AppCacheJob;