Ensure tests have an active task runner

chrome/browser/content_settings/content_settings_default_provider_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/memory/scoped_ptr.h"
 #include "base/message_loop/message_loop.h"
 #include "base/prefs/pref_service.h"
 #include "base/prefs/scoped_user_pref_update.h"
 #include "base/prefs/testing_pref_service.h"
 #include "chrome/browser/content_settings/content_settings_mock_observer.h"
 #include "chrome/common/pref_names.h"
 #include "chrome/test/base/testing_profile.h"
 #include "components/content_settings/core/browser/content_settings_default_provider.h"
 #include "components/content_settings/core/browser/content_settings_utils.h"
 #include "components/content_settings/core/test/content_settings_test_utils.h"
+#include "content/public/test/test_browser_thread_bundle.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "url/gurl.h"
 
 using ::testing::_;
 
 class DefaultProviderTest : public testing::Test {
  public:
   DefaultProviderTest()
       : provider_(profile_.GetPrefs(), false) {
   }
   ~DefaultProviderTest() override { provider_.ShutdownOnUIThread(); }
 
  protected:
+  content::TestBrowserThreadBundle thread_bundle_;
   TestingProfile profile_;
   content_settings::DefaultProvider provider_;
 };
 
 TEST_F(DefaultProviderTest, DefaultValues) {
   // Check setting defaults.
   EXPECT_EQ(CONTENT_SETTING_ALLOW,
             GetContentSetting(&provider_,
                               GURL(),
                               GURL(),
@@ skipping 256 matching lines @@
 
   default_settings_dictionary->GetIntegerWithoutPathExpansion(
       content_settings::GetTypeName(CONTENT_SETTINGS_TYPE_JAVASCRIPT),
       &js_setting);
   has_cd_setting = default_settings_dictionary->HasKey(
       content_settings::GetTypeName(CONTENT_SETTINGS_TYPE_SSL_CERT_DECISIONS));
 
   EXPECT_EQ(CONTENT_SETTING_BLOCK, IntToContentSetting(js_setting));
   EXPECT_FALSE(has_cd_setting);
 }