Adding defensive CHECKs for AudioDecoderConfig crash

media/filters/chunk_demuxer.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/filters/chunk_demuxer.h"
 
 #include <algorithm>
 #include <limits>
 #include <utility>
 
@@ skipping 266 matching lines @@
 DemuxerStream::Type ChunkDemuxerStream::type() const { return type_; }
 
 DemuxerStream::Liveness ChunkDemuxerStream::liveness() const {
   base::AutoLock auto_lock(lock_);
   return liveness_;
 }
 
 AudioDecoderConfig ChunkDemuxerStream::audio_decoder_config() {
   CHECK_EQ(type_, AUDIO);
   base::AutoLock auto_lock(lock_);
+  // Trying to track down crash. http://crbug.com/715761
+  CHECK(stream_);
   return stream_->GetCurrentAudioDecoderConfig();
 }
 
 VideoDecoderConfig ChunkDemuxerStream::video_decoder_config() {
   CHECK_EQ(type_, VIDEO);
   base::AutoLock auto_lock(lock_);
+  // Trying to track down crash. http://crbug.com/715761
+  CHECK(stream_);
   return stream_->GetCurrentVideoDecoderConfig();
 }
 
 bool ChunkDemuxerStream::SupportsConfigChanges() { return true; }
 
 VideoRotation ChunkDemuxerStream::video_rotation() {
   return VIDEO_ROTATION_0;
 }
 
 bool ChunkDemuxerStream::IsEnabled() const {
@@ skipping 1053 matching lines @@
 }
 
 void ChunkDemuxer::ShutdownAllStreams() {
   for (auto itr = source_state_map_.begin(); itr != source_state_map_.end();
        ++itr) {
     itr->second->Shutdown();
   }
 }
 
 }  // namespace media