PPAPI: Force async callback invocation option.

ppapi/cpp/dev/directory_reader_dev.cc

-// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Copyright (c) 2011 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 "ppapi/cpp/dev/directory_reader_dev.h"
 
 #include "ppapi/c/pp_errors.h"
 #include "ppapi/cpp/completion_callback.h"
 #include "ppapi/cpp/dev/directory_entry_dev.h"
 #include "ppapi/cpp/dev/file_ref_dev.h"
 #include "ppapi/cpp/module.h"
@@ skipping 16 matching lines @@
       directory_ref.pp_resource()));
 }
 
 DirectoryReader_Dev::DirectoryReader_Dev(const DirectoryReader_Dev& other)
     : Resource(other) {
 }
 
 int32_t DirectoryReader_Dev::GetNextEntry(DirectoryEntry_Dev* entry,
                                           const CompletionCallback& cc) {
   if (!has_interface<PPB_DirectoryReader_Dev>())
-    return PP_ERROR_NOINTERFACE;
+    return cc.MayForce(PP_ERROR_NOINTERFACE);
   return get_interface<PPB_DirectoryReader_Dev>()->GetNextEntry(
       pp_resource(), &entry->data_, cc.pp_completion_callback());
 }
 
 }  // namespace pp