Make blocking_task_runner_ a member variable instead of sequence_token_.

chrome/browser/chromeos/gdata/gdata_system_service.h

Index: chrome/browser/chromeos/gdata/gdata_system_service.h
===================================================================
--- chrome/browser/chromeos/gdata/gdata_system_service.h	(revision 148059)
+++ chrome/browser/chromeos/gdata/gdata_system_service.h	(working copy)
@@ -5,6 +5,8 @@
 #ifndef CHROME_BROWSER_CHROMEOS_GDATA_GDATA_SYSTEM_SERVICE_H_
 #define CHROME_BROWSER_CHROMEOS_GDATA_GDATA_SYSTEM_SERVICE_H_
 
+#include <string>
+
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/singleton.h"
 #include "base/threading/sequenced_worker_pool.h"
@@ -66,7 +68,7 @@
   friend class GDataSystemServiceFactory;
 
   Profile* profile_;
-  const base::SequencedWorkerPool::SequenceToken sequence_token_;
+  scoped_refptr<base::SequencedTaskRunner> blocking_task_runner_;
   GDataCache* cache_;
   scoped_ptr<DocumentsServiceInterface> documents_service_;
   scoped_ptr<GDataUploader> uploader_;