Have content/ create and destroy its own threads.

chrome/browser/content_settings/cookie_settings_unittest.cc

 // 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 "base/auto_reset.h"
 #include "base/command_line.h"
+#include "base/message_loop.h"
 #include "chrome/browser/content_settings/cookie_settings.h"
 #include "chrome/browser/prefs/pref_service.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/content_settings_pattern.h"
 #include "chrome/common/pref_names.h"
 #include "chrome/test/base/testing_profile.h"
 #include "content/test/test_browser_thread.h"
 #include "googleurl/src/gurl.h"
 #include "net/base/static_cookie_policy.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ skipping 236 matching lines @@
   CookieSettings* cookie_settings = CookieSettings::GetForProfile(&profile);
   profile.GetPrefs()->SetBoolean(prefs::kBlockThirdPartyCookies, true);
 
   // XHRs stemming from extensions are exempt from third-party cookie blocking
   // rules (as the first party is always the extension's security origin).
   EXPECT_TRUE(cookie_settings->IsSettingCookieAllowed(
       kBlockedSite, kExtensionURL));
 }
 
 }  // namespace