Update Native Client Authors to be Chromium Authors for the code moved from the

ppapi/native_client/src/shared/ppapi_proxy/plugin_ppb_file_ref.cc

-// Copyright (c) 2011 The Native Client 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 "native_client/src/shared/ppapi_proxy/plugin_ppb_file_ref.h"
 
 #include <string.h>
 #include <cmath>
 #include <string>
 
 #include "native_client/src/include/nacl_scoped_ptr.h"
@@ skipping 235 matching lines @@
     GetPath,
     GetParent,
     MakeDirectory,
     Touch,
     Delete,
     Rename
   };
   return &file_ref_interface;
 }
 }  // namespace ppapi_proxy