media: Use native DecodeStatus in media mojo interfaces

media/base/decode_status.h

 // Copyright 2016 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 MEDIA_BASE_DECODE_STATUS_H_
 #define MEDIA_BASE_DECODE_STATUS_H_
 
 #include <iosfwd>
 
 #include "media/base/media_export.h"
 
 namespace media {
 
 enum class DecodeStatus {
   OK = 0,        // Everything went as planned.
   ABORTED,       // Read aborted due to Reset() during pending read.
   DECODE_ERROR,  // Decoder returned decode error. Note: Prefixed by DECODE_
                  // since ERROR is a reserved name (special macro) on Windows.
+  DECODE_STATUS_MAX = DECODE_ERROR
 };
 
 // Helper function so that DecodeStatus can be printed easily.
 MEDIA_EXPORT std::ostream& operator<<(std::ostream& os,
                                       const DecodeStatus& status);
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_DECODE_STATUS_H_