Ensure tests have an active task runner

chrome/browser/metrics/thread_watcher_unittest.cc

 // Copyright (c) 2012 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 <math.h>
 
 #include "base/basictypes.h"
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 294 matching lines @@
     ThreadWatcherList::DeleteAll();
     io_watcher_ = NULL;
     db_watcher_ = NULL;
     io_thread_.reset();
     db_thread_.reset();
     watchdog_thread_.reset();
     thread_watcher_list_ = NULL;
   }
 
  private:
+  base::MessageLoop message_loop_;
   base::Lock lock_;
   base::ConditionVariable setup_complete_;
   bool initialized_;
   scoped_ptr<content::TestBrowserThread> db_thread_;
   scoped_ptr<content::TestBrowserThread> io_thread_;
   scoped_ptr<WatchDogThread> watchdog_thread_;
 };
 
 // Define static constants.
 const TimeDelta ThreadWatcherTest::kSleepTime =
@@ skipping 404 matching lines @@
       FROM_HERE,
       message_loop_for_ui.QuitClosure(),
       base::TimeDelta::FromSeconds(
           ThreadWatcherList::g_initialize_delay_seconds));
   message_loop_for_ui.Run();
 
   CheckState(false /* has_thread_watcher_list */,
              true /* stopped */,
              "Stopped");
 }