[ObjC ARC] Converts ios/chrome/browser/passwords:unit_tests to ARC.

ios/chrome/browser/passwords/password_controller_js_unittest.mm

 // Copyright 2013 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 <Foundation/Foundation.h>
 
 #import "ios/chrome/browser/passwords/js_password_manager.h"
 #import "ios/web/public/test/web_js_test.h"
 #import "ios/web/public/test/web_test_with_web_state.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "testing/gtest_mac.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 // Unit tests for ios/chrome/browser/web/resources/password_controller.js
 namespace {
 
 // Text fixture to test password controller.
 class PasswordControllerJsTest
     : public web::WebJsTest<web::WebTestWithWebState> {
  public:
   PasswordControllerJsTest()
       : web::WebJsTest<web::WebTestWithWebState>(@[ @"password_controller" ]) {}
 };
@@ skipping 268 matching lines @@
            "\"usernameValue\":\"\","
            "\"passwords\":[{\"element\":\"password\",\"value\":\"\"}]}",
           base_url.c_str()];
   EXPECT_NSEQ(
       result,
       ExecuteJavaScriptWithFormat(
           @"__gCrWeb.stringify(__gCrWeb.getPasswordFormData(%@))", parameter));
 };
 
 }  // namespace