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

ios/chrome/browser/ui/error_page_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 <EarlGrey/EarlGrey.h>
 
 #include "components/strings/grit/components_strings.h"
 #import "ios/chrome/test/app/chrome_test_util.h"
 #include "ios/chrome/test/app/web_view_interaction_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"
 #import "ios/web/public/test/http_server.h"
 #import "ios/web/public/test/earl_grey/web_view_matchers.h"
 #include "ios/web/public/test/http_server_util.h"
 #include "ios/web/public/test/response_providers/data_response_provider.h"
 #include "ios/web/public/test/response_providers/error_page_response_provider.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/base/l10n/l10n_util_mac.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 using chrome_test_util::OmniboxText;
 using chrome_test_util::StaticHtmlViewContainingText;
 using chrome_test_util::TapWebViewElementWithId;
 using chrome_test_util::WebViewContainingText;
 
 using web::test::HttpServer;
 
 // Tests display of error pages for bad URLs.
 @interface ErrorPageTestCase : ChromeTestCase
 
@@ skipping 142 matching lines @@
   [ChromeEarlGrey loadURL:URL];
   TapWebViewElementWithId(kButtonId);
   // Check that the timer has completed.
   [[EarlGrey selectElementWithMatcher:WebViewContainingText(kTimerCompleted)]
       assertWithMatcher:grey_notNil()];
   // DNS error page should still not appear.
   [self checkErrorPageIsNotVisible];
 }
 
 @end