IPC: Remove unnecessary conversions of BrokerableAttachment.

ipc/attachment_broker_privileged_win.h

 // 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.
 
 #ifndef IPC_ATTACHMENT_BROKER_PRIVILEGED_WIN_H_
 #define IPC_ATTACHMENT_BROKER_PRIVILEGED_WIN_H_
 
 #include "ipc/attachment_broker_privileged.h"
 #include "ipc/handle_attachment_win.h"
 #include "ipc/ipc_export.h"
 
 namespace IPC {
 
 // This class is a concrete subclass of AttachmentBrokerPrivileged for the
 // Windows platform.
 class IPC_EXPORT AttachmentBrokerPrivilegedWin
     : public AttachmentBrokerPrivileged {
  public:
   AttachmentBrokerPrivilegedWin();
   ~AttachmentBrokerPrivilegedWin() override;
 
   // IPC::AttachmentBroker overrides.
-  bool SendAttachmentToProcess(BrokerableAttachment* attachment,
-                               base::ProcessId destination_process) override;
+  bool SendAttachmentToProcess(
+      const scoped_refptr<IPC::BrokerableAttachment>& attachment,
+      base::ProcessId destination_process) override;
 
   // IPC::Listener overrides.
   bool OnMessageReceived(const Message& message) override;
 
  private:
   using HandleWireFormat = internal::HandleAttachmentWin::WireFormat;
   // IPC message handlers.
   void OnDuplicateWinHandle(const Message& message);
 
   // Duplicates |wire_Format| from |source_process| into its destination
   // process.
   HandleWireFormat DuplicateWinHandle(const HandleWireFormat& wire_format,
                                       base::ProcessId source_process);
 
   // Copies an existing |wire_format|, but substitutes in a different handle.
   HandleWireFormat CopyWireFormat(const HandleWireFormat& wire_format,
                                   int handle);
 
   // If the HANDLE's destination is this process, queue it and notify the
   // observers. Otherwise, send it in an IPC to its destination.
   void RouteDuplicatedHandle(const HandleWireFormat& wire_format);
 
   DISALLOW_COPY_AND_ASSIGN(AttachmentBrokerPrivilegedWin);
 };
 
 }  // namespace IPC
 
 #endif  // IPC_ATTACHMENT_BROKER_PRIVILEGED_WIN_H_