[ObjC ARC] Converts ios/chrome/app/safe_mode:unit_tests to ARC.

ios/chrome/app/safe_mode/safe_mode_coordinator_unittest.mm

 // Copyright 2016 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/app/safe_mode/safe_mode_coordinator.h"
 
 #import <UIKit/UIKit.h>
 
-#include "base/mac/scoped_nsobject.h"
 #include "testing/gtest_mac.h"

[sdefresne, 2017/02/21 09:45:36]

Can this be changed to the following?

#include "testing/gtest/include/gtest/gtest.h"

[stkhapugin, 2017/02/21 12:23:04]

Done.

 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 TEST(SafeModeCoordinatorTest, RootVC) {
   // Expect that starting a safe mode coordinator will populate the root view
   // controller.
-  base::scoped_nsobject<UIWindow> window(
-      [[UIWindow alloc] initWithFrame:CGRectMake(0, 0, 100, 100)]);
+  UIWindow* window =
+      [[UIWindow alloc] initWithFrame:CGRectMake(0, 0, 100, 100)];
   EXPECT_TRUE([window rootViewController] == nil);
-  base::scoped_nsobject<SafeModeCoordinator> safe_mode_coordinator(
-      [[SafeModeCoordinator alloc] initWithWindow:window]);
+  SafeModeCoordinator* safe_mode_coordinator =
+      [[SafeModeCoordinator alloc] initWithWindow:window];
   [safe_mode_coordinator start];
   EXPECT_FALSE([window rootViewController] == nil);
 }