Make offline directory name public.

ios/chrome/browser/reading_list/url_downloader.h

Index: ios/chrome/browser/reading_list/url_downloader.h
diff --git a/ios/chrome/browser/reading_list/url_downloader.h b/ios/chrome/browser/reading_list/url_downloader.h
index b378c76a2e5d62775c2a590c850127dc708e3d54..f5518c1b7a46ce2647607e1f4a9953c20b79bc4a 100644
--- a/ios/chrome/browser/reading_list/url_downloader.h
+++ b/ios/chrome/browser/reading_list/url_downloader.h
@@ -21,6 +21,10 @@ namespace dom_distiller {
 class DomDistillerService;
 }
 
+// This string contains the directory name in which offline pages are saved.
+// The directory is located in the profile directory.
+extern const char kReadingListOfflineDirectory[];
+
 // This class downloads and deletes offline versions of URLs using DOM distiller
 // to fetch the page and simplify it. Only one item is downloaded or deleted at
 // a time using a queue of tasks that are handled sequentially. Items (page +