Use ScopedTaskEnvironment instead of MessageLoopForUI in components tests.

components/history/core/test/history_backend_db_base_test.h

 // Copyright 2015 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.
 
 #ifndef COMPONENTS_HISTORY_CORE_TEST_HISTORY_BACKEND_DB_BASE_TEST_H_
 #define COMPONENTS_HISTORY_CORE_TEST_HISTORY_BACKEND_DB_BASE_TEST_H_
 
 #include <stdint.h>
 
 #include <memory>
 
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/files/scoped_temp_dir.h"
 #include "base/memory/ref_counted.h"
-#include "base/message_loop/message_loop.h"
+#include "base/test/scoped_task_environment.h"
 #include "components/history/core/test/history_unittest_base.h"
 #include "sql/init_status.h"
 
 namespace base {
 class Time;
 }
 
 namespace history {
 
 class BackendDelegate;
@@ skipping 25 matching lines @@
 
   void DeleteBackend();
 
   bool AddDownload(uint32_t id,
                    const std::string& guid,
                    DownloadState state,
                    base::Time time);
 
   base::ScopedTempDir temp_dir_;
 
-  base::MessageLoopForUI message_loop_;
+  base::test::ScopedTaskEnvironment scoped_task_environment_;
 
   // names of the database files
   base::FilePath history_dir_;
 
   // Created via CreateBackendAndDatabase.
   scoped_refptr<HistoryBackend> backend_;
   std::unique_ptr<InMemoryHistoryBackend> in_mem_backend_;
   HistoryDatabase* db_;  // Cached reference to the backend's database.
   sql::InitStatus last_profile_error_;
 };
 
 }  // namespace history
 
 #endif  // COMPONENTS_HISTORY_CORE_TEST_HISTORY_BACKEND_DB_BASE_TEST_H_