Separate JumpListIcons delete task and update task

chrome/browser/win/jumplist.h

 // Copyright (c) 2012 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 CHROME_BROWSER_WIN_JUMPLIST_H_
 #define CHROME_BROWSER_WIN_JUMPLIST_H_
 
 #include <stddef.h>
 
 #include <list>
@@ skipping 14 matching lines @@
 #include "components/history/core/browser/top_sites_observer.h"
 #include "components/keyed_service/core/refcounted_keyed_service.h"
 #include "components/sessions/core/tab_restore_service.h"
 #include "components/sessions/core/tab_restore_service_observer.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 
 namespace base {
 class SingleThreadTaskRunner;
+class SequencedTaskRunner;
 }
 
 namespace chrome {
 struct FaviconImageResult;
 }
 
 class JumpListFactory;
 class PrefChangeRegistrar;
 class Profile;
 
@@ skipping 133 matching lines @@
   // Timer for requesting delayed updates of the jumplist.
   base::OneShotTimer timer_;
 
   // Holds data that can be accessed from multiple threads.
   scoped_refptr<base::RefCountedData<JumpListData>> jumplist_data_;
 
   // Id of last favicon task. It's used to cancel current task if a new one
   // comes in before it finishes.
   base::CancelableTaskTracker::TaskId task_id_;
 
-  // A task runner running tasks to update the jumplist in JumpListIcons and to
-  // delete JumpListIconsOld sequentially.
-  scoped_refptr<base::SingleThreadTaskRunner> single_thread_task_runner_;
+  // A task runner running tasks to update the jumplist in JumpListIcons.
+  scoped_refptr<base::SingleThreadTaskRunner> update_jumplisticons_task_runner_;
+
+  // A task runner running tasks to delete JumpListIconsOld directory.
+  scoped_refptr<base::SequencedTaskRunner> delete_jumplisticonsold_task_runner_;
 
   // For callbacks may be run after destruction.
   base::WeakPtrFactory<JumpList> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(JumpList);
 };
 
 #endif  // CHROME_BROWSER_WIN_JUMPLIST_H_