Convert to new enter method

ppapi/thunk/ppb_flash_clipboard_thunk.cc

 // 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.
 
 #include "ppapi/c/pp_errors.h"
 #include "ppapi/c/private/ppb_flash_clipboard.h"
 #include "ppapi/thunk/enter.h"
 #include "ppapi/thunk/thunk.h"
 #include "ppapi/thunk/ppb_flash_clipboard_api.h"
 
@@ skipping 19 matching lines @@
   if (enter.failed())
     return PP_MakeUndefined();
   return enter.functions()->ReadPlainText(instance, clipboard_type);
 }
 
 int32_t WritePlainText(PP_Instance instance,
                        PP_Flash_Clipboard_Type clipboard_type,
                        PP_Var text) {
   EnterFlashClipboard enter(instance, true);
   if (enter.failed())
-    return PP_ERROR_NOINTERFACE;
+    return enter.retval();
   return enter.functions()->WritePlainText(instance, clipboard_type, text);
 }
 
 const PPB_Flash_Clipboard g_ppb_flash_clipboard_thunk = {
   &IsFormatAvailable,
   &ReadPlainText,
   &WritePlainText
 };
 
 }  // namespace
 
 const PPB_Flash_Clipboard_3_0* GetPPB_Flash_Clipboard_3_0_Thunk() {
   return &g_ppb_flash_clipboard_thunk;
 }
 
 }  // namespace thunk
 }  // namespace ppapi