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

ios/chrome/browser/autofill/form_input_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/strings/sys_string_conversions.h"
 #import "base/test/ios/wait_util.h"
 #include "ios/chrome/browser/autofill/form_input_accessory_view_controller.h"
 #include "ios/chrome/browser/ui/ui_util.h"
 #include "ios/chrome/grit/ios_strings.h"
 #import "ios/chrome/test/app/chrome_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"
 #import "ios/testing/wait_util.h"
 #import "ios/web/public/test/earl_grey/web_view_actions.h"
 #import "ios/web/public/test/earl_grey/web_view_matchers.h"
 #import "ios/web/public/test/http_server.h"
 #include "ios/web/public/test/http_server_util.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace {
 
 const char kFormElementId1[] = "username";
 const char kFormElementId2[] = "otherstuff";
 
 // If an element is focused in the webview, returns its ID. Returns an empty
 // NSString otherwise.
 NSString* GetFocusedElementId() {
   NSString* js = @"(function() {"
                   "  return document.activeElement.id;"
                   "})();";
-  NSError* error = nil;
+  __unsafe_unretained NSError* error = nil;
   NSString* result = chrome_test_util::ExecuteJavaScript(js, &error);
   GREYAssertTrue(!error, @"Unexpected error when executing JavaScript.");
   return result;
 }
 
 // Verifies that |elementId| is the selected element in the web page.
 void AssertElementIsFocused(const std::string& element_id) {
   NSString* description =
       [NSString stringWithFormat:@"Timeout waiting for the focused element in "
                                  @"the webview to be \"%@\"",
@@ skipping 106 matching lines @@
 // visible doesn't crash the browser.
 - (void)testCloseKeyboardWhenNotVisible {
   FormInputAccessoryViewController* inputAccessoryViewController =
       chrome_test_util::GetInputAccessoryViewController();
   GREYAssertNotNil(inputAccessoryViewController,
                    @"The tab's input accessory view should not be non nil.");
   [inputAccessoryViewController closeKeyboardWithoutButtonPress];
 }
 
 @end