Remove IPC::BrokerableAttachment.

ipc/ipc_mojo_handle_attachment.h

 // Copyright (c) 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_IPC_MOJO_HANDLE_ATTACHMENT_H_
 #define IPC_IPC_MOJO_HANDLE_ATTACHMENT_H_
 
 #include "base/files/file.h"
 #include "base/macros.h"
 #include "build/build_config.h"
 #include "ipc/ipc_export.h"
 #include "ipc/ipc_message_attachment.h"
 #include "mojo/public/cpp/system/handle.h"
 
 namespace IPC {
 
 namespace internal {
 
 // A MessageAttachment that holds a MojoHandle.
 // This can hold any type of transferrable Mojo handle (i.e. message pipe, data
 // pipe, etc), but the receiver is expected to know what type of handle to
 // expect.
 class IPC_EXPORT MojoHandleAttachment : public MessageAttachment {
  public:
   explicit MojoHandleAttachment(mojo::ScopedHandle handle);
 
   Type GetType() const override;
 
-#if defined(OS_POSIX)
-  // Should not be called.
-  base::PlatformFile TakePlatformFile() override;
-#endif  // OS_POSIX
-
   // Returns the owning handle transferring the ownership.
   mojo::ScopedHandle TakeHandle();
 
  private:
   ~MojoHandleAttachment() override;
   mojo::ScopedHandle handle_;
 
   DISALLOW_COPY_AND_ASSIGN(MojoHandleAttachment);
 };
 
 }  // namespace internal
 }  // namespace IPC
 
 #endif  // IPC_IPC_MOJO_HANDLE_ATTACHMENT_H_