[ObjC ARC] Converts ios/web/public/test/fakes:fakes to ARC.

ios/web/public/test/fakes/test_web_state_delegate.mm

 // Copyright 2017 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 "ios/web/public/test/fakes/test_web_state_delegate.h"
 
 #include "base/memory/ptr_util.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace web {
 
 TestOpenURLRequest::TestOpenURLRequest()
     : params(GURL(),
              Referrer(),
              WindowOpenDisposition::UNKNOWN,
              ui::PAGE_TRANSITION_LINK,
              false) {}
 
 TestOpenURLRequest::~TestOpenURLRequest() = default;
@@ skipping 92 matching lines @@
   return &java_script_dialog_presenter_;
 }
 
 void TestWebStateDelegate::OnAuthRequired(
     WebState* source,
     NSURLProtectionSpace* protection_space,
     NSURLCredential* credential,
     const AuthCallback& callback) {
   last_authentication_request_ = base::MakeUnique<TestAuthenticationRequest>();
   last_authentication_request_->web_state = source;
-  last_authentication_request_->protection_space.reset(
-      [protection_space retain]);
-  last_authentication_request_->credential.reset([credential retain]);
+  last_authentication_request_->protection_space = protection_space;
+  last_authentication_request_->credential = credential;
   last_authentication_request_->auth_callback = callback;
 }
 
 }  // namespace web