[Offline Pages] Feature flag to allow concurrent background loading on svelte

components/offline_pages/offline_page_feature.h

Index: components/offline_pages/offline_page_feature.h
diff --git a/components/offline_pages/offline_page_feature.h b/components/offline_pages/offline_page_feature.h
index 98c1b27e911d469a2b43ba6c6b1824309e16c607..7b5ce2b580c1ba272400d8393806028a77ea10a3 100644
--- a/components/offline_pages/offline_page_feature.h
+++ b/components/offline_pages/offline_page_feature.h
@@ -13,6 +13,7 @@ namespace offline_pages {
 extern const base::Feature kOfflineBookmarksFeature;
 extern const base::Feature kOffliningRecentPagesFeature;
 extern const base::Feature kOfflinePagesBackgroundLoadingFeature;
+extern const base::Feature kOfflinePagesSvelteConcurrentLoadingFeature;
 extern const base::Feature kOfflinePagesCTFeature;
 extern const base::Feature kOfflinePagesSharingFeature;
 extern const base::Feature kBackgroundLoaderForDownloadsFeature;
@@ -32,6 +33,9 @@ bool IsOfflinePagesCTEnabled();
 // Returns true if offline page sharing is enabled.
 bool IsOfflinePagesSharingEnabled();
 
+// Returns true if concurrent background loading is enabled for svelte.
+bool IsOfflinePagesSvelteConcurrentLoadingEnabled();
+
 bool IsBackgroundLoaderForDownloadsEnabled();
 
 }  // namespace offline_pages