Create a secondary file thread, FILE_USER_BLOCKING...

content/shell/shell_browser_main.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/shell/shell_browser_main.h"
 
 #include "base/message_loop.h"
 #include "base/threading/thread.h"
 #include "base/threading/thread_restrictions.h"
 #include "content/browser/browser_process_sub_thread.h"
@@ skipping 22 matching lines @@
     io_thread()->message_loop()->PostTask(
         FROM_HERE,
         NewRunnableFunction(&base::ThreadRestrictions::SetIOAllowed, true));
 
   browser_context_.reset();
 
   resource_dispatcher_host_->download_file_manager()->Shutdown();
   resource_dispatcher_host_->save_file_manager()->Shutdown();
   resource_dispatcher_host_->Shutdown();
   io_thread_.reset();
+  appcache_thread_.reset();
   cache_thread_.reset();
   process_launcher_thread_.reset();
   file_thread_.reset();
   resource_dispatcher_host_.reset();  // Kills WebKit thread.
   db_thread_.reset();
 }
 
 void ShellBrowserMainParts::PreMainMessageLoopRun() {
   db_thread_.reset(new BrowserProcessSubThread(BrowserThread::DB));
   db_thread_->Start();
   file_thread_.reset(new BrowserProcessSubThread(BrowserThread::FILE));
   file_thread_->Start();
   process_launcher_thread_.reset(
       new BrowserProcessSubThread(BrowserThread::PROCESS_LAUNCHER));
   process_launcher_thread_->Start();
 
   base::Thread::Options options;
   options.message_loop_type = MessageLoop::TYPE_IO;
 
   cache_thread_.reset(new BrowserProcessSubThread(BrowserThread::CACHE));
   cache_thread_->StartWithOptions(options);
+  appcache_thread_.reset(new BrowserProcessSubThread(BrowserThread::APPCACHE));

[rvargas (doing something else), 2011/10/21 19:46:17]

and here

+  appcache_thread_->Start();
   io_thread_.reset(new BrowserProcessSubThread(BrowserThread::IO));
   io_thread_->StartWithOptions(options);
 
   browser_context_.reset(new ShellBrowserContext(this));
 
   Shell::PlatformInitialize();
   net::NetModule::SetResourceProvider(Shell::PlatformResourceProvider);
 
   Shell::CreateNewWindow(browser_context_.get(),
                          GURL("http://www.google.com"),
@@ skipping 12 matching lines @@
   return resource_dispatcher_host_.get();
 }
 
 ui::Clipboard* ShellBrowserMainParts::GetClipboard() {
   if (!clipboard_.get())
     clipboard_.reset(new ui::Clipboard());
   return clipboard_.get();
 }
 
 }  // namespace