Ensure tests have an active task runner

chrome/browser/supervised_user/legacy/supervised_user_shared_settings_update_unittest.cc

 // Copyright 2014 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/bind.h"
 #include "base/memory/scoped_ptr.h"
 #include "chrome/browser/supervised_user/legacy/supervised_user_shared_settings_service.h"
 #include "chrome/browser/supervised_user/legacy/supervised_user_shared_settings_update.h"
 #include "chrome/test/base/testing_profile.h"
+#include "content/public/test/test_browser_thread_bundle.h"
 #include "sync/api/sync_change.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 class SupervisedUserSharedSettingsUpdateTest : public testing::Test {
  public:
   SupervisedUserSharedSettingsUpdateTest() : service_(profile_.GetPrefs()) {}
   ~SupervisedUserSharedSettingsUpdateTest() override {}
 
   void OnSettingUpdated(bool success) {
     result_.reset(new bool(success));
   }
 
  protected:
+  content::TestBrowserThreadBundle thread_bundle_;
   TestingProfile profile_;
   SupervisedUserSharedSettingsService service_;
   scoped_ptr<bool> result_;
 };
 
 TEST_F(SupervisedUserSharedSettingsUpdateTest, Success) {
   SupervisedUserSharedSettingsUpdate update(
       &service_,
       "abcdef",
       "name",
@@ skipping 43 matching lines @@
         &service_,
         "abcdef",
         "name",
         scoped_ptr<base::Value>(new base::StringValue("Hans Moleman")),
         base::Bind(&SupervisedUserSharedSettingsUpdateTest::OnSettingUpdated,
                    base::Unretained(this)));
     ASSERT_FALSE(result_);
   }
   ASSERT_FALSE(result_);
 }