Revert 116816 - Hook up the SequencedWorkerPool to the browser thread.

content/browser/browser_main_loop.cc

Index: content/browser/browser_main_loop.cc
===================================================================
--- content/browser/browser_main_loop.cc	(revision 116816)
+++ content/browser/browser_main_loop.cc	(working copy)
@@ -497,14 +497,6 @@
       parts_->PostStopThread(id);
   }
 
-  // Close the blocking I/O pool after the other threads. Other threads such
-  // as the I/O thread may need to schedule work like closing files or flushing
-  // data during shutdown, so the blocking pool needs to be available. There
-  // may also be slow operations pending that will blcok shutdown, so closing
-  // it here (which will block until required operations are complete) gives
-  // more head start for those operations to finish.
-  BrowserThreadImpl::ShutdownThreadPool();
-
   if (parts_.get())
     parts_->PostDestroyThreads();
 }