ui: Cleanup class/struct forward declarations

components/offline_pages/offline_page_feature.cc

Index: components/offline_pages/offline_page_feature.cc
diff --git a/components/offline_pages/offline_page_feature.cc b/components/offline_pages/offline_page_feature.cc
index c469846124d11c98ca28a60808c2173f253e38d4..b4620fc13ea57c78383ed8738b5be7983af317c6 100644
--- a/components/offline_pages/offline_page_feature.cc
+++ b/components/offline_pages/offline_page_feature.cc
@@ -32,6 +32,10 @@ const base::Feature kOfflinePagesSharingFeature{
 const base::Feature kBackgroundLoaderForDownloadsFeature{
     "BackgroundLoadingForDownloads", base::FEATURE_ENABLED_BY_DEFAULT};
 
+const base::Feature kOfflinePagesAsyncDownloadFeature {
+   "OfflinePagesAsyncDownload", base::FEATURE_DISABLED_BY_DEFAULT
+};
+
 bool IsOfflineBookmarksEnabled() {
   return base::FeatureList::IsEnabled(kOfflineBookmarksFeature);
 }
@@ -56,4 +60,8 @@ bool IsBackgroundLoaderForDownloadsEnabled() {
   return base::FeatureList::IsEnabled(kBackgroundLoaderForDownloadsFeature);
 }
 
+bool IsOfflinePagesAsyncDownloadEnabled() {
+  return base::FeatureList::IsEnabled(kOfflinePagesAsyncDownloadFeature);
+}
+
 }  // namespace offline_pages