Revert of Remove header dependencies from sequence_checker.h to sequenced_worker_pool.h

chrome/browser/ui/browser_list.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_UI_BROWSER_LIST_H_
 #define CHROME_BROWSER_UI_BROWSER_LIST_H_
 
 #include <stddef.h>
 
 #include <vector>
 
-#include "base/callback_forward.h"
 #include "base/lazy_instance.h"
 #include "base/macros.h"
 #include "base/observer_list.h"
 
 class Browser;
 class Profile;
 
 namespace base {
 class FilePath;
 }
@@ skipping 125 matching lines @@
   // removal across all BrowserLists.
   static base::LazyInstance<
       base::ObserverList<chrome::BrowserListObserver>>::Leaky observers_;
 
   static BrowserList* instance_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowserList);
 };
 
 #endif  // CHROME_BROWSER_UI_BROWSER_LIST_H_