Fix PP_FileOpenFlags_Dev handling:

ppapi/tests/test_file_ref.cc

 // 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/tests/test_file_ref.h"
 
 #include <stdio.h>
 
 #include "ppapi/c/pp_errors.h"
 #include "ppapi/c/dev/ppb_file_io_dev.h"
@@ skipping 307 matching lines @@
   pp::FileSystem_Dev file_system(instance_, PP_FILESYSTEMTYPE_LOCALTEMPORARY);
   int32_t rv = file_system.Open(1024, callback);
   if (rv == PP_OK_COMPLETIONPENDING)
     rv = callback.WaitForResult();
   if (rv != PP_OK)
     return ReportError("FileSystem::Open", rv);
 
   pp::FileRef_Dev file_ref(file_system, "/file_touch");
   pp::FileIO_Dev file_io(instance_);
   rv = file_io.Open(file_ref,
-                    PP_FILEOPENFLAG_CREATE | PP_FILEOPENFLAG_WRITE,
+                    PP_FILEOPENFLAG_CREATE |
+                    PP_FILEOPENFLAG_TRUNCATE |
+                    PP_FILEOPENFLAG_WRITE,
                     callback);
   if (rv == PP_OK_COMPLETIONPENDING)
     rv = callback.WaitForResult();
   if (rv != PP_OK)
     return ReportError("FileIO::Open", rv);
 
   // Write some data to have a non-zero file size.
   rv = file_io.Write(0, "test", 4, callback);
   if (rv == PP_OK_COMPLETIONPENDING)
     rv = callback.WaitForResult();
@@ skipping 217 matching lines @@
   if (rv == PP_OK_COMPLETIONPENDING) {
     rv = callback.WaitForResult();
     if (rv != PP_ERROR_ABORTED)
       return "FileSystem::Rename not aborted.";
   } else if (rv != PP_OK) {
     return ReportError("FileSystem::Rename", rv);
   }
 
   PASS();
 }