[scheduling] Use ScopedTaskEnvironment instead of MessageLoop in ntp_tiles

MessageLoop will go away, eventually.

BUG=891670

Change-Id: I6b2246cf59b8454ab0a6522bc7825bbcd9e76e12
Reviewed-on: https://chromium-review.googlesource.com/c/1352368Reviewed-by: Marc Treib <treib@chromium.org>
Commit-Queue: Carlos Caballero <carlscab@google.com>
Cr-Commit-Position: refs/heads/master@{#612207}

components/ntp_tiles/most_visited_sites_unittest.cc

@@ -17,11 +17,11 @@
 #include "base/callback_list.h"
 #include "base/command_line.h"
 #include "base/macros.h"
-#include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/task/cancelable_task_tracker.h"
 #include "base/test/scoped_feature_list.h"
+#include "base/test/scoped_task_environment.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "build/build_config.h"
 #include "components/history/core/browser/top_sites.h"
@@ -535,7 +535,7 @@ class MostVisitedSitesTest : public ::testing::TestWithParam<bool> {
       suggestions_service_callbacks_;
   TopSitesCallbackList top_sites_callbacks_;
 
-  base::MessageLoop message_loop_;
+  base::test::ScopedTaskEnvironment task_environment_;
   sync_preferences::TestingPrefServiceSyncable pref_service_;
   PopularSitesFactoryForTest popular_sites_factory_;
   scoped_refptr<StrictMock<MockTopSites>> mock_top_sites_;

components/ntp_tiles/popular_sites_impl_unittest.cc

@@ -13,12 +13,12 @@
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/json/json_writer.h"
-#include "base/message_loop/message_loop.h"
 #include "base/optional.h"
 #include "base/run_loop.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/test/scoped_feature_list.h"
+#include "base/test/scoped_task_environment.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/values.h"
 #include "build/build_config.h"
@@ -211,7 +211,8 @@ class PopularSitesTest : public ::testing::Test {
   const TestPopularSite kYouTube;
   const TestPopularSite kChromium;
 
-  base::MessageLoopForUI ui_loop_;
+  base::test::ScopedTaskEnvironment task_environment_{
+      base::test::ScopedTaskEnvironment::MainThreadType::UI};
   std::unique_ptr<sync_preferences::TestingPrefServiceSyncable> prefs_;
   network::TestURLLoaderFactory test_url_loader_factory_;
   scoped_refptr<network::SharedURLLoaderFactory> test_shared_loader_factory_;