media: Use native BufferingState in media mojo interfaces

media/base/buffering_state.h

 // Copyright 2014 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_BUFFERING_STATE_H_
 #define MEDIA_BASE_BUFFERING_STATE_H_
 
 #include "base/callback_forward.h"
 
 namespace media {
 
 enum BufferingState {
   // Indicates that there is no data buffered.
   //
   // Typical reason is data underflow and hence playback should be paused.
   BUFFERING_HAVE_NOTHING,
 
   // Indicates that enough data has been buffered.
   //
   // Typical reason is enough data has been prerolled to start playback.
   BUFFERING_HAVE_ENOUGH,
+
+  BUFFERING_STATE_MAX = BUFFERING_HAVE_ENOUGH,
 };
 
 // Used to indicate changes in buffering state;
 typedef base::Callback<void(BufferingState)> BufferingStateCB;
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_BUFFERING_STATE_H_