[Offline pages] Enabling notifications for pages saved later

components/offline_pages/background/request_notifier.h

Index: components/offline_pages/background/request_notifier.h
diff --git a/components/offline_pages/background/request_notifier.h b/components/offline_pages/background/request_notifier.h
index dfdc76e1074f740be022592f4c0a24852fb28557..25daaca053410ecc141f1f30c2ec5508b8eff964 100644
--- a/components/offline_pages/background/request_notifier.h
+++ b/components/offline_pages/background/request_notifier.h
@@ -23,6 +23,8 @@ class RequestNotifier {
     REMOVED,
   };
 
+  virtual ~RequestNotifier() = default;
+
   // Notifies observers that |request| has been added.
   virtual void NotifyAdded(const SavePageRequest& request) = 0;