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

ios/chrome/browser/web/http_auth_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/sys_string_conversions.h"
 #include "components/strings/grit/components_strings.h"
 #include "ios/chrome/browser/ui/ui_util.h"
 #include "ios/chrome/grit/ios_strings.h"
 #include "ios/chrome/test/app/navigation_test_util.h"
 #import "ios/chrome/test/earl_grey/chrome_matchers.h"
 #import "ios/chrome/test/earl_grey/chrome_test_case.h"
 #import "ios/testing/wait_util.h"
 #import "ios/web/public/test/http_server.h"
 #include "ios/web/public/test/http_server_util.h"
 #import "ios/web/public/test/response_providers/http_auth_response_provider.h"
 #include "ui/base/l10n/l10n_util_mac.h"
 #include "url/gurl.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 using testing::WaitUntilConditionOrTimeout;
 using testing::kWaitForPageLoadTimeout;
 using chrome_test_util::WebViewContainingText;
 
 namespace {
 
 // Returns matcher for HTTP Authentication dialog.
 id<GREYMatcher> HttpAuthDialog() {
   NSString* title = l10n_util::GetNSStringWithFixup(IDS_LOGIN_DIALOG_TITLE);
   return chrome_test_util::StaticTextWithAccessibilityLabel(title);
@@ skipping 105 matching lines @@
   chrome_test_util::LoadUrl(URL);
   WaitForHttpAuthDialog();
 
   [[EarlGrey selectElementWithMatcher:chrome_test_util::CancelButton()]
       performAction:grey_tap()];
   [[EarlGrey selectElementWithMatcher:HttpAuthDialog()]
       assertWithMatcher:grey_nil()];
 }
 
 @end