Use an explicit boolean has_new_first_party_for_cookies instead...

chrome/common/render_messages_internal.h

 // Copyright (c) 2009 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.
 
 // This header is meant to be included in multiple passes, hence no traditional
 // header guard.
 // See ipc_message_macros.h for explanation of the macros and passes.
 
 #include <map>
 #include <string>
@@ skipping 1036 matching lines @@
   IPC_MESSAGE_ROUTED2(ViewHostMsg_RequestResource,
                       int /* request_id */,
                       ViewHostMsg_Resource_Request)
 
   // Cancels a resource request with the ID given as the parameter.
   IPC_MESSAGE_ROUTED1(ViewHostMsg_CancelRequest,
                       int /* request_id */)
 
   // Follows a redirect that occured for the resource request with the ID given
   // as the parameter.
-  IPC_MESSAGE_ROUTED2(ViewHostMsg_FollowRedirect,
+  IPC_MESSAGE_ROUTED3(ViewHostMsg_FollowRedirect,
                       int /* request_id */,
+                      bool /* has_new_first_party_for_cookies */,
                       GURL /* new_first_party_for_cookies */)
 
   // Makes a synchronous resource request via the browser.
   IPC_SYNC_MESSAGE_ROUTED2_1(ViewHostMsg_SyncLoad,
                              int /* request_id */,
                              ViewHostMsg_Resource_Request,
                              SyncLoadResult)
 
   // Used to set a cookie.  The cookie is set asynchronously, but will be
   // available to a subsequent ViewHostMsg_GetCookies request.
@@ skipping 966 matching lines @@
                               std::string /* signed public key and challenge */)
 
 #if defined(SPELLCHECKER_IN_RENDERER)
   // The renderer has tried to spell check a word, but couldn't because no
   // dictionary was available to load. Request that the browser find an
   // appropriate dictionary and return it.
   IPC_MESSAGE_CONTROL0(ViewHostMsg_SpellChecker_RequestDictionary)
 #endif
 
 IPC_END_MESSAGES(ViewHost)