[ObjC ARC] Converts ios/chrome/browser/ui/first_run:unit_tests to ARC.

ios/chrome/browser/ui/first_run/welcome_to_chrome_view_controller_unittest.mm

 // 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.
 
 #import <UIKit/UIKit.h>
 
 #include <memory>
 
-#include "base/mac/scoped_nsobject.h"
 #include "components/metrics/metrics_pref_names.h"
 #include "components/prefs/pref_registry_simple.h"
 #include "components/prefs/testing_pref_service.h"
 #include "ios/chrome/browser/browser_state/test_chrome_browser_state.h"
 #include "ios/chrome/browser/tabs/tab_model.h"
 #include "ios/chrome/browser/ui/fancy_ui/primary_action_button.h"
 #import "ios/chrome/browser/ui/first_run/welcome_to_chrome_view.h"
 #import "ios/chrome/browser/ui/first_run/welcome_to_chrome_view_controller.h"
 #include "ios/chrome/browser/ui/ui_util.h"
 #include "ios/chrome/test/ios_chrome_scoped_testing_local_state.h"
 #include "ios/web/public/test/test_web_thread_bundle.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "testing/gtest_mac.h"
 #include "testing/platform_test.h"
 #include "third_party/ocmock/OCMock/OCMock.h"
 #include "third_party/ocmock/gtest_support.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 @interface WelcomeToChromeView (ExposedForTesting)
 @property(nonatomic, retain, readonly) UIButton* checkBoxButton;
 - (void)checkBoxButtonWasTapped;
 @end
 
 namespace {
 
 class WelcomeToChromeViewControllerTest : public PlatformTest {
  protected:
   void SetUp() override {
     PlatformTest::SetUp();
     TestChromeBrowserState::Builder test_cbs_builder;
     chrome_browser_state_ = test_cbs_builder.Build();
     id tabModel = [OCMockObject mockForClass:[TabModel class]];
-    controller_.reset([[WelcomeToChromeViewController alloc]
+    controller_ = [[WelcomeToChromeViewController alloc]
         initWithBrowserState:chrome_browser_state_.get()
-                    tabModel:tabModel]);
+                    tabModel:tabModel];
     [controller_ loadView];
   }
 
   void TearDown() override {
-    controller_.reset();
+    controller_ = nil;
     PlatformTest::TearDown();
   }
 
   web::TestWebThreadBundle thread_bundle_;
   IOSChromeScopedTestingLocalState local_state_;
   std::unique_ptr<TestChromeBrowserState> chrome_browser_state_;
-  base::scoped_nsobject<WelcomeToChromeViewController> controller_;
+  WelcomeToChromeViewController* controller_;
 };
 
 TEST_F(WelcomeToChromeViewControllerTest, TestDefaultStatsCheckBoxValue) {
   BOOL checkbox_value =
       [WelcomeToChromeViewController defaultStatsCheckboxValue];
   ASSERT_TRUE(checkbox_value);
 }
 
 TEST_F(WelcomeToChromeViewControllerTest, TestConstructorDestructor) {
-  EXPECT_TRUE(controller_.get());
+  EXPECT_TRUE(controller_);
   EXPECT_TRUE([controller_ view]);
 }
 
 TEST_F(WelcomeToChromeViewControllerTest, TestToggleCheckbox) {
   WelcomeToChromeView* welcome_view =
       static_cast<WelcomeToChromeView*>([controller_ view]);
   EXPECT_TRUE(welcome_view.checkBoxButton.selected);
   [welcome_view checkBoxButtonWasTapped];
   EXPECT_FALSE(welcome_view.checkBoxButton.selected);
   [welcome_view checkBoxButtonWasTapped];
   EXPECT_TRUE(welcome_view.checkBoxButton.selected);
 }
 
 }  // namespace