Ensure tests have an active task runner

chrome/browser/search_engines/default_search_pref_migration_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 "chrome/browser/search_engines/default_search_pref_migration.h"
 
 #include <string>
 
 #include "base/compiler_specific.h"
 #include "base/files/scoped_temp_dir.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/prefs/pref_service.h"
 #include "base/strings/string16.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/common/pref_names.h"
 #include "chrome/test/base/testing_pref_service_syncable.h"
 #include "chrome/test/base/testing_profile.h"
 #include "components/search_engines/search_engines_pref_names.h"
 #include "components/search_engines/template_url.h"
 #include "components/search_engines/template_url_service.h"
+#include "content/public/test/test_browser_thread_bundle.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "url/gurl.h"
 
 class DefaultSearchPrefMigrationTest : public testing::Test {
  public:
   DefaultSearchPrefMigrationTest();
 
   // testing::Test:
   void SetUp() override;
 
   void SaveDefaultSearchProviderToLegacyPrefs(const TemplateURL* t_url);
 
   scoped_ptr<TemplateURL> CreateKeyword(const std::string& short_name,
                                         const std::string& keyword,
                                         const std::string& url);
 
   TestingProfile* profile() { return profile_.get(); }
 
   DefaultSearchManager* default_search_manager() {
     return default_search_manager_.get();
   }
 
  private:
+  content::TestBrowserThreadBundle thread_bundle_;
   base::ScopedTempDir temp_dir_;
   scoped_ptr<TestingProfile> profile_;
   scoped_ptr<DefaultSearchManager> default_search_manager_;
 
   DISALLOW_COPY_AND_ASSIGN(DefaultSearchPrefMigrationTest);
 };
 
 DefaultSearchPrefMigrationTest::DefaultSearchPrefMigrationTest() {
 }
 
@@ skipping 173 matching lines @@
   // Store a value in the legacy location.
   SaveDefaultSearchProviderToLegacyPrefs(&prepopulated_turl);
 
   // Run the migration.
   ConfigureDefaultSearchPrefMigrationToDictionaryValue(profile()->GetPrefs());
 
   // Test that the legacy value is not migrated, as it is not user-selected.
   default_search_manager()->GetDefaultSearchEngine(&source);
   EXPECT_EQ(DefaultSearchManager::FROM_FALLBACK, source);
 }