Create a secondary file thread, FILE_USER_BLOCKING...

content/browser/browser_thread_impl.cc

 // 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.
 
 #include "content/browser/browser_thread_impl.h"
 
 #include "base/atomicops.h"
 #include "base/bind.h"
 #include "base/lazy_instance.h"
 #include "base/message_loop.h"
 #include "base/message_loop_proxy.h"
 #include "base/threading/thread_restrictions.h"
 
 namespace content {
 
 namespace {
 
 // Friendly names for the well-known threads.
 static const char* g_browser_thread_names[BrowserThread::ID_COUNT] = {
   "",  // UI (name assembled in browser_main.cc).
   "Chrome_DBThread",  // DB
   "Chrome_WebKitThread",  // WEBKIT
   "Chrome_FileThread",  // FILE
+  "Chrome_FileUserBlockingThread",  // FILE_USER_BLOCKING
   "Chrome_ProcessLauncherThread",  // PROCESS_LAUNCHER
   "Chrome_CacheThread",  // CACHE
   "Chrome_IOThread",  // IO
 #if defined(OS_CHROMEOS)
   "Chrome_WebSocketproxyThread",  // WEB_SOCKET_PROXY
 #endif
 };
 
 // This lock protects |g_browser_threads|.  Do not read or modify that
 // array without holding this lock.  Do not block while holding this
@@ skipping 377 matching lines @@
   AtomicWord* storage = reinterpret_cast<AtomicWord*>(
       &g_browser_thread_delegates[identifier]);
   AtomicWord old_pointer = base::subtle::NoBarrier_AtomicExchange(
       storage, reinterpret_cast<AtomicWord>(delegate));
 
   // This catches registration when previously registered.
   DCHECK(!delegate || !old_pointer);
 }
 
 }  // namespace content