Create a secondary file thread, FILE_USER_BLOCKING...

chrome/browser/browser_process_impl.h

 // Copyright (c) 2011 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.
 
 // When each service is created, we set a flag indicating this. At this point,
 // the service initialization could fail or succeed. This allows us to remember
 // if we tried to create a service, and not try creating it over and over if
 // the creation failed.
 
 #ifndef CHROME_BROWSER_BROWSER_PROCESS_IMPL_H_
@@ skipping 48 matching lines @@
   void PreStopThread(content::BrowserThread::ID identifier);
   void PostStopThread(content::BrowserThread::ID identifier);
 
   base::Thread* process_launcher_thread();
 
   // BrowserProcess methods
   virtual void EndSession() OVERRIDE;
   virtual ResourceDispatcherHost* resource_dispatcher_host() OVERRIDE;
   virtual MetricsService* metrics_service() OVERRIDE;
   virtual IOThread* io_thread() OVERRIDE;
+  virtual base::Thread* file_user_blocking_thread() OVERRIDE;
   virtual base::Thread* file_thread() OVERRIDE;
   virtual base::Thread* db_thread() OVERRIDE;
   virtual base::Thread* cache_thread() OVERRIDE;
   virtual WatchDogThread* watchdog_thread() OVERRIDE;
 #if defined(OS_CHROMEOS)
   virtual base::Thread* web_socket_proxy_thread() OVERRIDE;
 #endif
   virtual ProfileManager* profile_manager() OVERRIDE;
   virtual PrefService* local_state() OVERRIDE;
   virtual SidebarManager* sidebar_manager() OVERRIDE;
@@ skipping 210 matching lines @@
 #if !defined(OS_CHROMEOS)
   scoped_ptr<ComponentUpdateService> component_updater_;
 
   scoped_refptr<CRLSetFetcher> crl_set_fetcher_;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(BrowserProcessImpl);
 };
 
 #endif  // CHROME_BROWSER_BROWSER_PROCESS_IMPL_H_