Fix intermittent DCHECK failure in BlacklistManagerTest.

chrome/browser/privacy_blacklist/blacklist_manager_unittest.cc

 // Copyright (c) 2009 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/privacy_blacklist/blacklist_manager.h"
 
 #include "base/message_loop.h"
 #include "base/path_service.h"
 #include "base/scoped_temp_dir.h"
 #include "base/thread.h"
@@ skipping 78 matching lines @@
         mock_file_thread_(ChromeThread::FILE) {
   }
 
   virtual void SetUp() {
     ASSERT_TRUE(PathService::Get(chrome::DIR_TEST_DATA, &test_data_dir_));
     test_data_dir_ = test_data_dir_.AppendASCII("blacklist_samples");
     ASSERT_TRUE(mock_file_thread_.Start());
   }
 
   virtual void TearDown() {
+    mock_file_thread_.Stop();
     loop_.RunAllPending();
   }
 
   // NotificationObserver
   virtual void Observe(NotificationType type,
                        const NotificationSource& source,
                        const NotificationDetails& details) {
     MessageLoop::current()->Quit();
   }
 
@@ skipping 136 matching lines @@
     WaitForBlacklistUpdate();
 
     // The manager should recompile the blacklist.
     const Blacklist* blacklist = manager->GetCompiledBlacklist();
     EXPECT_TRUE(BlacklistHasMatch(blacklist,
                                   "http://host/annoying_ads/ad.jpg"));
   }
 }
 
 }  // namespace