Use ScopedTaskEnvironment instead of MessageLoop in components unit tests.

components/history/core/browser/history_backend_unittest.cc

 // Copyright (c) 2012 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 "components/history/core/browser/history_backend.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <memory>
@@ skipping 12 matching lines @@
 #include "base/memory/ptr_util.h"
 #include "base/memory/ref_counted.h"
 #include "base/metrics/histogram_base.h"
 #include "base/metrics/histogram_samples.h"
 #include "base/metrics/statistics_recorder.h"
 #include "base/run_loop.h"
 #include "base/strings/string16.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/test/histogram_tester.h"
+#include "base/test/scoped_task_environment.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "build/build_config.h"
 #include "components/favicon_base/favicon_usage_data.h"
 #include "components/history/core/browser/history_backend_client.h"
 #include "components/history/core/browser/history_constants.h"
 #include "components/history/core/browser/history_database_params.h"
 #include "components/history/core/browser/history_service.h"
 #include "components/history/core/browser/history_service_observer.h"
 #include "components/history/core/browser/in_memory_database.h"
 #include "components/history/core/browser/in_memory_history_backend.h"
@@ skipping 232 matching lines @@
     mem_backend_.swap(backend);
   }
 
   // The types and details of notifications which were broadcasted.
   std::vector<GURL> favicon_changed_notifications_page_urls_;
   std::vector<GURL> favicon_changed_notifications_icon_urls_;
   URLVisitedList url_visited_notifications_;
   URLsModifiedList urls_modified_notifications_;
   URLsDeletedList urls_deleted_notifications_;
 
-  base::MessageLoop message_loop_;
+  base::test::ScopedTaskEnvironment scoped_task_environment_;
   base::FilePath test_dir_;
 
   DISALLOW_COPY_AND_ASSIGN(HistoryBackendTestBase);
 };
 
 void HistoryBackendTestDelegate::SetInMemoryBackend(
     std::unique_ptr<InMemoryHistoryBackend> backend) {
   test_->SetInMemoryBackend(std::move(backend));
 }
 
@@ skipping 3626 matching lines @@
   backend_->QueryMostVisitedURLs(100, 100, &most_visited);
 
   const base::string16 kSomeTitle;  // Ignored by equality operator.
   EXPECT_THAT(
       most_visited,
       ElementsAre(MostVisitedURL(GURL("http://example1.com"), kSomeTitle),
                   MostVisitedURL(GURL("http://example5.com"), kSomeTitle)));
 }
 
 }  // namespace history