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

ios/web/public/test/http_server/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.
 
 #import "ios/web/public/test/http_server/data_response_provider.h"
 
 #include "base/memory/ptr_util.h"
 #include "base/strings/sys_string_conversions.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace web {
 
 std::unique_ptr<net::test_server::HttpResponse>
 DataResponseProvider::GetEmbeddedTestServerResponse(const Request& request) {
   std::string response_body;
   scoped_refptr<net::HttpResponseHeaders> response_headers;
   GetResponseHeadersAndBody(request, &response_headers, &response_body);
 
   std::unique_ptr<net::test_server::BasicHttpResponse> data_response =
       base::MakeUnique<net::test_server::BasicHttpResponse>();
@@ skipping 11 matching lines @@
     if (name == "Content-type") {
       data_response->set_content_type(value);
       continue;
     }
     data_response->AddCustomHeader(name, value);
   }
   return std::move(data_response);
 }
 
 }  // namespace web