Revert of Remove IPC::BrokerableAttachment.

ipc/handle_win.cc

 // 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 "ipc/handle_win.h"
 
 #include <utility>
 
 #include "base/logging.h"
 #include "base/memory/ref_counted.h"
@@ skipping 20 matching lines @@
 
 // static
 bool ParamTraits<HandleWin>::Read(const base::Pickle* m,
                                   base::PickleIterator* iter,
                                   param_type* r) {
   scoped_refptr<base::Pickle::Attachment> base_attachment;
   if (!m->ReadAttachment(iter, &base_attachment))
     return false;
   MessageAttachment* attachment =
       static_cast<MessageAttachment*>(base_attachment.get());
-  if (attachment->GetType() != MessageAttachment::Type::WIN_HANDLE)
+  if (attachment->GetType() != MessageAttachment::TYPE_BROKERABLE_ATTACHMENT)
     return false;
+  BrokerableAttachment* brokerable_attachment =
+      static_cast<BrokerableAttachment*>(attachment);
+  if (brokerable_attachment->GetBrokerableType() !=
+      BrokerableAttachment::WIN_HANDLE) {
+    return false;
+  }
   IPC::internal::HandleAttachmentWin* handle_attachment =
-      static_cast<IPC::internal::HandleAttachmentWin*>(attachment);
+      static_cast<IPC::internal::HandleAttachmentWin*>(brokerable_attachment);
   r->set_handle(handle_attachment->get_handle());
   handle_attachment->reset_handle_ownership();
   return true;
 }
 
 // static
 void ParamTraits<HandleWin>::Log(const param_type& p, std::string* l) {
   l->append(base::StringPrintf("0x%p", p.get_handle()));
   l->append(base::IntToString(p.get_permissions()));
 }
 
 }  // namespace IPC