Create a secondary file thread, FILE_USER_BLOCKING...

content/browser/browser_main_loop.cc

Index: content/browser/browser_main_loop.cc
===================================================================
--- content/browser/browser_main_loop.cc	(revision 111751)
+++ content/browser/browser_main_loop.cc	(working copy)
@@ -323,6 +323,9 @@
         // this is fixed, we don't start the thread but still call
         // Pre/PostStartThread for the ID.
         break;
+      case BrowserThread::FILE_USER_BLOCKING:
+        thread_to_start = &file_user_blocking_thread_;
+        break;
       case BrowserThread::FILE:
         thread_to_start = &file_thread_;
 #if defined(OS_WIN)
@@ -446,6 +449,9 @@
         // this is fixed, we don't stop the thread but still call
         // Pre/PostStopThread for the ID.
         break;
+      case BrowserThread::FILE_USER_BLOCKING:
+        thread_to_stop = &file_user_blocking_thread_;
+        break;
       case BrowserThread::FILE:
         thread_to_stop = &file_thread_;
         break;