Fix DCHECK error on mac buildbot.

chrome/browser/ui/cocoa/cocoa_profile_test.mm

 // 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 "chrome/browser/ui/cocoa/cocoa_profile_test.h"
 
 #include "chrome/browser/browser_process.h"
 #include "chrome/test/base/testing_browser_process.h"
 #include "content/test/test_browser_thread.h"
 
@@ skipping 21 matching lines @@
   // were to delete the ProfileManager, the UI thread would at that point no
   // longer exist.
   static_cast<TestingBrowserProcess*>(g_browser_process)->SetProfileManager(
       NULL);
 
   // Make sure any pending tasks run before we destroy other threads.
   message_loop_.RunAllPending();
 
   // Drop any new tasks for the IO and FILE threads.
   io_thread_.reset();
+  file_user_blocking_thread_.reset();
   file_thread_.reset();
-  file_user_blocking_thread_.reset();
 
   message_loop_.RunAllPending();
 }
 
 void CocoaProfileTest::SetUp() {
   CocoaTest::SetUp();
 
   ASSERT_TRUE(profile_manager_.SetUp());
 
   profile_ = profile_manager_.CreateTestingProfile("default");
@@ skipping 27 matching lines @@
 }
 
 void CocoaProfileTest::CloseBrowserWindow() {
   // Check to make sure a window was actually created.
   DCHECK(browser_->window());
   browser_->CloseAllTabs();
   browser_->CloseWindow();
   // |browser_| will be deleted by its BrowserWindowController.
   ignore_result(browser_.release());
 }