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

ios/chrome/browser/web/stop_loading_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 "base/memory/ptr_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/time/time.h"
 #include "ios/chrome/browser/ui/ui_util.h"
 #include "ios/chrome/test/app/navigation_test_util.h"
 #import "ios/chrome/test/earl_grey/chrome_earl_grey_ui.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"
 #include "ios/web/public/test/http_server_util.h"
 #include "ios/web/public/test/response_providers/html_response_provider.h"
 #include "url/gurl.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 using chrome_test_util::ButtonWithAccessibilityLabelId;
 using chrome_test_util::WebViewContainingText;
 
 namespace {
 
 // Text appearing on the navigation test page.
 const char kPageText[] = "Navigation testing page";
 
 // Response provider that serves the page which never finishes loading.
 class InfinitePendingResponseProvider : public HtmlResponseProvider {
@@ skipping 100 matching lines @@
   if (!IsIPadIdiom()) {
     [ChromeEarlGreyUI openToolsMenu];
   }
   [[EarlGrey selectElementWithMatcher:chrome_test_util::StopButton()]
       assertWithMatcher:grey_notVisible()];
   [[EarlGrey selectElementWithMatcher:chrome_test_util::ReloadButton()]
       assertWithMatcher:grey_sufficientlyVisible()];
 }
 
 @end