[Reading List] Check web state after the distillation delay.

ios/chrome/browser/reading_list/reading_list_distiller_page.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef IOS_CHROME_BROWSER_READING_LIST_READING_LIST_DISTILLER_PAGE_H_
 #define IOS_CHROME_BROWSER_READING_LIST_READING_LIST_DISTILLER_PAGE_H_
 
 #include <memory>
 #include <string>
 
@@ skipping 68 matching lines @@
   // triggers a navigation to it. Stop distillation of the page there as the new
   // load will trigger a new distillation.
   bool HandleGoogleCachedAMPPageJavaScriptResult(id result, id error);
   // Continue the distillation on the page that is currently loaded in
   // |CurrentWebState()|.
   void ContinuePageDistillation();
   // Starts the fetching of |page_url|'s favicon.
   void FetchFavicon(const GURL& page_url);
 
   // Continues distillation by calling superclass |OnLoadURLDone|.
-  void DelayedOnLoadURLDone();
+  void DelayedOnLoadURLDone(int delayed_task_id);
   GURL original_url_;
 
   FaviconWebStateDispatcher* web_state_dispatcher_;
   ReadingListDistillerPageDelegate* delegate_;
+  int delayed_task_id_;
   base::WeakPtrFactory<ReadingListDistillerPage> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ReadingListDistillerPage);
 };
 
 }  // namespace reading_list
 
 #endif  // IOS_CHROME_BROWSER_READING_LIST_READING_LIST_DISTILLER_PAGE_H_