Remove calls to IsRunningSequenceOnCurrentThread() in wallpaper API.

chrome/browser/chromeos/extensions/wallpaper_api.h

 // Copyright 2013 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_CHROMEOS_EXTENSIONS_WALLPAPER_API_H_
 #define CHROME_BROWSER_CHROMEOS_EXTENSIONS_WALLPAPER_API_H_
 
 #include <memory>
 
 #include "base/threading/sequenced_worker_pool.h"
@@ skipping 46 matching lines @@
   std::unique_ptr<extensions::api::wallpaper::SetWallpaper::Params> params_;
 
   // Unique file name of the custom wallpaper.
   std::string file_name_;
 
   // User id of the user who initiate this API call.
   AccountId account_id_ = EmptyAccountId();
 
   // Id used to identify user wallpaper files on hard drive.
   wallpaper::WallpaperFilesId wallpaper_files_id_;
-
-  // Sequence token associated with wallpaper operations. Shared with
-  // WallpaperManager.
-  base::SequencedWorkerPool::SequenceToken sequence_token_;
 };
 
 #endif  // CHROME_BROWSER_CHROMEOS_EXTENSIONS_WALLPAPER_API_H_