Converts ios/web/net to ARC.

ios/web/net/request_group_util.mm

 // Copyright 2014 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/net/request_group_util.h"
 
 #include <Foundation/Foundation.h>
 
 #include "base/base64.h"
 #include "base/logging.h"
 #include "base/rand_util.h"
 #include "base/strings/sys_string_conversions.h"
 #import "net/base/mac/url_conversions.h"
 #include "url/gurl.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace {
 // Minimum length for a request group ID. A shorter string is considered as an
 // invalid ID.
 const int kMinimumIDLength = 5;
 }
 
 namespace web {
 
 // Generates a request-group ID used to correlate web requests with the embedder
 // that triggered it. It is important that the return value should not be unique
@@ skipping 80 matching lines @@
     return request_group_id;
   if (application_scheme &&
       [[request.mainDocumentURL scheme]
           caseInsensitiveCompare:application_scheme] == NSOrderedSame) {
     return ExtractRequestGroupIDFromURL(request.mainDocumentURL);
   }
   return nil;
 }
 
 }  // namespace web