Queued ClearBlackList() shouldn't use weak pointer.

components/previews/core/previews_black_list.cc

Index: components/previews/core/previews_black_list.cc
diff --git a/components/previews/core/previews_black_list.cc b/components/previews/core/previews_black_list.cc
index fd1afed3b0ad23b33e14584d4e4fb0188546e89e..b391e04e571a1177466ac91d673230ecdb4e3903 100644
--- a/components/previews/core/previews_black_list.cc
+++ b/components/previews/core/previews_black_list.cc
@@ -89,8 +89,7 @@ void PreviewsBlackList::ClearBlackList(base::Time begin_time,
     ClearBlackListSync(begin_time, end_time);
   } else {
     QueuePendingTask(base::Bind(&PreviewsBlackList::ClearBlackListSync,
-                                weak_factory_.GetWeakPtr(), begin_time,
-                                end_time));
+                                base::Unretained(this), begin_time, end_time));
   }
 }