[ObjC ARC] Converts ios/chrome/browser/ui/stack_view:eg_tests to ARC.

ios/chrome/browser/ui/stack_view/stack_view_egtest.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 <XCTest/XCTest.h>
 
 #include "base/ios/block_types.h"
 #include "base/mac/foundation_util.h"
 #include "base/strings/sys_string_conversions.h"
 #import "base/test/ios/wait_util.h"
 #include "ios/chrome/browser/browser_state/chrome_browser_state.h"
 #include "ios/chrome/browser/pref_names.h"
 #import "ios/chrome/browser/tabs/tab.h"
 #import "ios/chrome/browser/tabs/tab_model.h"
 #import "ios/chrome/browser/ui/browser_view_controller.h"
 #import "ios/chrome/browser/ui/stack_view/card_view.h"
 #import "ios/chrome/browser/ui/stack_view/stack_view_controller.h"
 #import "ios/chrome/browser/ui/stack_view/stack_view_controller_private.h"
 #import "ios/chrome/browser/ui/toolbar/toolbar_controller.h"
 #import "ios/chrome/browser/ui/tools_menu/tools_menu_view_controller.h"
 #import "ios/chrome/test/app/stack_view_test_util.h"
 #import "ios/chrome/test/app/tab_test_util.h"
 #import "ios/chrome/test/earl_grey/chrome_earl_grey.h"
 #import "ios/chrome/test/earl_grey/chrome_matchers.h"
 #import "ios/chrome/test/earl_grey/chrome_test_case.h"
 #include "ios/testing/earl_grey/disabled_test_macros.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace {
 // Returns a GREYMatcher that matches |view|.
 // TODO(crbug.com/642619): Evaluate whether this should be shared code.
 id<GREYMatcher> ViewMatchingView(UIView* view) {
   MatchesBlock matches = ^BOOL(UIView* viewToMatch) {
     return viewToMatch == view;
   };
   DescribeToBlock describe = ^void(id<GREYDescription> description) {
     NSString* matcherDescription =
         [NSString stringWithFormat:@"View matching %@", view];
@@ skipping 202 matching lines @@
       chrome_test_util::GetStackViewController();
   GREYAssert([stackViewController isCurrentSetIncognito],
              @"Incognito deck not selected.");
   // Switch back to the main CardSet and verify that is selected.
   ShowDeckWithType(DeckType::NORMAL);
   GREYAssert(![stackViewController isCurrentSetIncognito],
              @"Normal deck not selected.");
 }
 
 @end