Adding defensive CHECKs for AudioDecoderConfig crash

media/filters/chunk_demuxer.cc

Index: media/filters/chunk_demuxer.cc
diff --git a/media/filters/chunk_demuxer.cc b/media/filters/chunk_demuxer.cc
index 149e1e498e683492bcce5d83d6a0fc28f360471d..f9db61f3e3b32c1fe6603c4f3f1b0125184cfcb7 100644
--- a/media/filters/chunk_demuxer.cc
+++ b/media/filters/chunk_demuxer.cc
@@ -284,12 +284,16 @@ DemuxerStream::Liveness ChunkDemuxerStream::liveness() const {
 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();
 }