Create a secondary file thread, FILE_USER_BLOCKING...

chrome/browser/browser_process.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.
 
 // This interface is for managing the global services of the application. Each
 // service is lazily created when requested the first time. The service getters
 // will return NULL if the service is not available, so callers must check for
 // this condition.
 
 #ifndef CHROME_BROWSER_BROWSER_PROCESS_H_
@@ skipping 129 matching lines @@
   // It might be nicer to have a thread pool for this kind of thing.
   virtual base::Thread* file_thread() = 0;
 
   // Returns the thread that is used for database operations such as the web
   // database. History has its own thread since it has much higher traffic.
   virtual base::Thread* db_thread() = 0;
 
   // Returns the thread that is used for background cache operations.
   virtual base::Thread* cache_thread() = 0;
 
+  // Returns the thread that is used for background appcache operations.
+  virtual base::Thread* appcache_thread() = 0;
+
   // Returns the thread that is used for health check of all browser threads.
   virtual WatchDogThread* watchdog_thread() = 0;
 
 #if defined(OS_CHROMEOS)
   // Returns thread for websocket to TCP proxy.
   // TODO(dilmah): remove this thread.  Instead provide this functionality via
   // hooks into websocket bridge layer.
   virtual base::Thread* web_socket_proxy_thread() = 0;
 #endif
 
@@ skipping 87 matching lines @@
 
   virtual CRLSetFetcher* crl_set_fetcher() = 0;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(BrowserProcess);
 };
 
 extern BrowserProcess* g_browser_process;
 
 #endif  // CHROME_BROWSER_BROWSER_PROCESS_H_