Add RequestOSFileHandle as a private PPAPI

ppapi/cpp/private/file_io_private.h

Index: ppapi/cpp/private/file_io_private.h
diff --git a/ppapi/cpp/private/file_io_private.h b/ppapi/cpp/private/file_io_private.h
new file mode 100644
index 0000000000000000000000000000000000000000..6a861225c2c671c16c1e86a619f7628bdd6e7bce
--- /dev/null
+++ b/ppapi/cpp/private/file_io_private.h
@@ -0,0 +1,30 @@
+// Copyright (c) 2013 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 PPAPI_CPP_PRIVATE_FILE_IO_PRIVATE_H_
+#define PPAPI_CPP_PRIVATE_FILE_IO_PRIVATE_H_
+
+#include <string>
+
+#include "ppapi/c/pp_stdint.h"
+#include "ppapi/c/private/pp_file_handle.h"
+#include "ppapi/cpp/completion_callback.h"
+
+namespace pp {
+
+class FileIO;
+
+class FileIO_Private {
+ public:
+  /// Creates a FileIO_Private object.
+  FileIO_Private();
+
+  int32_t GetOSFileHandle(const FileIO& file_io,

[dmichael (off chromium), 2013/03/27 19:40:53]

This feels a little funny to me. If we go this route, it might as well just be a
static function.

What we've done in the past was actually inheritance...  e.g. InstancePrivate
inherits Instance, and adds the additional Private functions. Same for
Var/VarPrivate. Could you do that here?

[hamaji, 2013/03/28 00:17:29]

Done.

+                          PP_FileHandle* result_handle,
+                          const CompletionCallback& cc);
+};
+
+}  // namespace pp
+
+#endif  // PPAPI_CPP_PRIVATE_FILE_IO_PRIVATE_H_