Remove use of void** from HttpResponseHeaders::EnumerateHeaderLines

ios/web/public/test/response_providers/data_response_provider.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/test/response_providers/data_response_provider.h"
 
 #include "base/strings/sys_string_conversions.h"
 #import "ios/third_party/gcdwebserver/src/GCDWebServer/Responses/GCDWebServerDataResponse.h"
 
 namespace web {
 
 GCDWebServerResponse* DataResponseProvider::GetGCDWebServerResponse(
     const Request& request) {
   std::string response_body;
   scoped_refptr<net::HttpResponseHeaders> response_headers;
   GetResponseHeadersAndBody(request, &response_headers, &response_body);
   GCDWebServerDataResponse* data_response = [GCDWebServerDataResponse
       responseWithHTML:base::SysUTF8ToNSString(response_body)];
   data_response.statusCode = response_headers->response_code();
-  void* iter = nullptr;
+  size_t iter = 0;
   std::string name;
   std::string value;
   while (response_headers->EnumerateHeaderLines(&iter, &name, &value)) {
     // TODO(crbug.com/435350): Extract out other names that can't be set by
     // using the |setValue:forAdditionalHeader:| API such as "ETag" etc.
     if (name == "Content-type") {
       data_response.contentType = base::SysUTF8ToNSString(value);
       continue;
     }
     [data_response setValue:base::SysUTF8ToNSString(value)
         forAdditionalHeader:base::SysUTF8ToNSString(name)];
   }
   return data_response;
 }
 
 }  // namespace web