[ARC] Converts parts of ios/web/web_state to ARC.

ios/web/web_state/js/credential_util.mm

 // Copyright 2015 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.
 
 #include "ios/web/public/web_state/js/credential_util.h"
 
 #include "base/logging.h"
 #include "base/strings/string16.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/values.h"
 #include "ios/web/public/web_state/credential.h"
 #include "url/gurl.h"
 #include "url/origin.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace {
 
 // "type" value for a DictionaryValue representation of PasswordCredential.
 const char* kPasswordCredentialType = "PasswordCredential";
 
 // "type" value for a DictionaryValue representation of FederatedCredential.
 const char* kFederatedCredentialType = "FederatedCredential";
 
 }  // namespace
 
@@ skipping 73 matching lines @@
       break;
     default:
       NOTREACHED();
   }
   value->SetString("id", credential.id);
   value->SetString("name", credential.name);
   value->SetString("avatarURL", credential.avatar_url.spec());
 }
 
 }  // web