Use ScopedTaskEnvironment instead of MessageLoopForUI in ios tests.

ios/chrome/browser/ui/settings/voicesearch_collection_view_controller_unittest.mm

 // Copyright 2013 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.
 
 #import "ios/chrome/browser/ui/settings/voicesearch_collection_view_controller.h"
 
 #include <memory>
 
 #include "base/compiler_specific.h"
 #include "base/files/file_path.h"
 #include "base/mac/foundation_util.h"
-#include "base/message_loop/message_loop.h"
+#include "base/test/scoped_task_environment.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "components/prefs/pref_member.h"
 #include "components/prefs/pref_registry_simple.h"
 #include "components/prefs/testing_pref_service.h"
 #import "ios/chrome/browser/ui/collection_view/cells/collection_view_switch_item.h"
 #import "ios/chrome/browser/ui/collection_view/collection_view_controller.h"
 #import "ios/chrome/browser/ui/collection_view/collection_view_controller_test.h"
 #include "ios/chrome/browser/voice/speech_input_locale_config_impl.h"
 #include "ios/public/provider/chrome/browser/voice/voice_search_prefs.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #import "testing/gtest_mac.h"
 #include "testing/platform_test.h"
 #include "ui/base/l10n/l10n_util_mac.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
 #endif
 
 namespace {
 
 class VoicesearchCollectionViewControllerTest
     : public CollectionViewControllerTest {
  protected:
+  VoicesearchCollectionViewControllerTest()
+      : scoped_task_environment_(
+            base::test::ScopedTaskEnvironment::MainThreadType::UI) {}
+
   void SetUp() override {
     CollectionViewControllerTest::SetUp();
     pref_service_ = CreateLocalState();
   }
 
   CollectionViewController* InstantiateController() override {
     return [[VoicesearchCollectionViewController alloc]
         initWithPrefs:pref_service_.get()];
   }
 
   std::unique_ptr<PrefService> CreateLocalState() {
     TestingPrefServiceSimple* prefs = new TestingPrefServiceSimple();
     PrefRegistrySimple* registry = prefs->registry();
     registry->RegisterBooleanPref(prefs::kVoiceSearchTTS, false);
     registry->RegisterStringPref(prefs::kVoiceSearchLocale, "en-US");
     return std::unique_ptr<PrefService>(prefs);
   }
 
   CollectionViewSwitchCell* GetSwitchCell() {
     return base::mac::ObjCCastStrict<CollectionViewSwitchCell>(
         [controller().collectionView
             cellForItemAtIndexPath:[NSIndexPath indexPathForItem:0
                                                        inSection:0]]);
   }
 
-  base::MessageLoopForUI message_loop_;
+  base::test::ScopedTaskEnvironment scoped_task_environment_;
   std::unique_ptr<PrefService> pref_service_;
 };
 
 TEST_F(VoicesearchCollectionViewControllerTest, NumberOfSectionsAndItems) {
   CreateController();
   CheckController();
 
   EXPECT_EQ(2, NumberOfSections());
   EXPECT_EQ(1, NumberOfItemsInSection(0));
   const std::vector<voice::SpeechInputLocale>& locales =
@@ skipping 68 matching lines @@
   textToSpeechEnabled.Init(prefs::kVoiceSearchTTS, pref_service_.get());
   textToSpeechEnabled.SetValue(true);
 
   CreateController();
   CollectionViewSwitchItem* switchItem = GetCollectionViewItem(0, 0);
   EXPECT_TRUE(switchItem.isOn);
   EXPECT_FALSE(switchItem.isEnabled);
 }
 
 }  // namespace