Add RequestOSFileHandle as a private PPAPI

ppapi/api/trusted/ppb_file_io_trusted.idl

 /* 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.
  */
 
 /*
  * This file defines the trusted file IO interface
  */
 
 label Chrome {
   M14= 0.4
 };
 
 // Available only to trusted implementations.
 interface PPB_FileIOTrusted {
   /**
    * Returns a file descriptor corresponding to the given FileIO object. On
    * Windows, returns a HANDLE; on all other platforms, returns a POSIX file
    * descriptor. The FileIO object must have been opened with a successful
    * call to FileIO::Open.  The file descriptor will be closed automatically
    * when the FileIO object is closed or destroyed.
+   *
+   * TODO(hamaji): Remove this and use GetOSFileHandle instead.
    */
   int32_t GetOSFileDescriptor([in] PP_Resource file_io);
 
   /**
    * Notifies the browser that underlying file will be modified.  This gives
    * the browser the opportunity to apply quota restrictions and possibly
    * return an error to indicate that the write is not allowed.
    */
   int32_t WillWrite([in] PP_Resource file_io,
                     [in] int64_t offset,
@@ skipping 10 matching lines @@
    * Write and SetLength calls.  WillChangeFileSize would require the caller to
    * compute the file size resulting from a Write call, which may be
    * undesirable.
    */
   int32_t WillSetLength([in] PP_Resource file_io,
                         [in] int64_t length,
                         [in] PP_CompletionCallback callback);
 
 };