Adding VP8 Alpha support in Media Source

media/webm/webm_parser.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 "media/webm/webm_parser.h"
 
 // This file contains code to parse WebM file elements. It was created
 // from information in the Matroska spec.
 // http://www.matroska.org/technical/specs/index.html
 // This file contains code for encrypted WebM. Current WebM
@@ skipping 161 matching lines @@
 
 static const ElementIdInfo kTrackTranslateIds[] = {
   {UINT, kWebMIdTrackTranslateEditionUID},
   {UINT, kWebMIdTrackTranslateCodec},
   {BINARY, kWebMIdTrackTranslateTrackID},
 };
 
 static const ElementIdInfo kVideoIds[] = {
   {UINT, kWebMIdFlagInterlaced},
   {UINT, kWebMIdStereoMode},
+  {UINT, kWebMIdAlphaMode},
   {UINT, kWebMIdPixelWidth},
   {UINT, kWebMIdPixelHeight},
   {UINT, kWebMIdPixelCropBottom},
   {UINT, kWebMIdPixelCropTop},
   {UINT, kWebMIdPixelCropLeft},
   {UINT, kWebMIdPixelCropRight},
   {UINT, kWebMIdDisplayWidth},
   {UINT, kWebMIdDisplayHeight},
   {UINT, kWebMIdDisplayUnit},
   {UINT, kWebMIdAspectRatioType},
@@ skipping 741 matching lines @@
       if (kSegmentIds[i].id_ == id_b)
         return true;
     }
   }
 
   // kWebMIdSegment siblings.
   return ((id_b == kWebMIdSegment) || (id_b == kWebMIdEBMLHeader));
 }
 
 }  // namespace media