libvpx: Pull from upstream

source/libvpx/webmdec.cc

 /*
  *  Copyright (c) 2013 The WebM project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 76 matching lines @@
   const mkvparser::VideoTrack* video_track = NULL;
   for (unsigned long i = 0; i < tracks->GetTracksCount(); ++i) {
     const mkvparser::Track* const track = tracks->GetTrackByIndex(i);
     if (track->GetType() == mkvparser::Track::kVideo) {
       video_track = static_cast<const mkvparser::VideoTrack*>(track);
       webm_ctx->video_track_index = track->GetNumber();
       break;
     }
   }
 
-  if (video_track == NULL) {
+  if (video_track == NULL || video_track->GetCodecId() == NULL) {
     rewind_and_reset(webm_ctx, vpx_ctx);
     return 0;
   }
 
   if (!strncmp(video_track->GetCodecId(), "V_VP8", 5)) {
     vpx_ctx->fourcc = VP8_FOURCC;
   } else if (!strncmp(video_track->GetCodecId(), "V_VP9", 5)) {
     vpx_ctx->fourcc = VP9_FOURCC;
   } else if (!strncmp(video_track->GetCodecId(), "V_VP10", 6)) {
     vpx_ctx->fourcc = VP10_FOURCC;
@@ skipping 114 matching lines @@
   webm_ctx->block_frame_index = 0;
   webm_ctx->timestamp_ns = 0;
   webm_ctx->reached_eos = 0;
 
   return 0;
 }
 
 void webm_free(struct WebmInputContext *webm_ctx) {
   reset(webm_ctx);
 }