Revert of Remove IPC::BrokerableAttachment.

ipc/ipc_message_utils.cc

 // Copyright (c) 2012 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 "ipc/ipc_message_utils.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include "base/files/file_path.h"
@@ skipping 639 matching lines @@
     return false;
 
   // TODO(morrita): Seems like this should return false.
   if (!valid)
     return true;
 
   scoped_refptr<base::Pickle::Attachment> attachment;
   if (!m->ReadAttachment(iter, &attachment))
     return false;
 
-  if (static_cast<MessageAttachment*>(attachment.get())->GetType() !=
-      MessageAttachment::Type::PLATFORM_FILE) {
-    return false;
-  }
-
   *r = base::FileDescriptor(
-      static_cast<internal::PlatformFileAttachment*>(attachment.get())
-          ->TakePlatformFile(),
+      static_cast<MessageAttachment*>(attachment.get())->TakePlatformFile(),
       true);
   return true;
 }
 
 void ParamTraits<base::FileDescriptor>::Log(const param_type& p,
                                             std::string* l) {
   if (p.auto_close) {
     l->append(base::StringPrintf("FD(%d auto-close)", p.fd));
   } else {
     l->append(base::StringPrintf("FD(%d)", p.fd));
@@ skipping 557 matching lines @@
   return result;
 }
 
 void ParamTraits<MSG>::Log(const param_type& p, std::string* l) {
   l->append("<MSG>");
 }
 
 #endif  // OS_WIN
 
 }  // namespace IPC