Updated some comments to point at bugs in ffmpeg_unittest.cc and ffmpeg_audio_decoder.cc.

media/filters/ffmpeg_audio_decoder.cc

Index: media/filters/ffmpeg_audio_decoder.cc
diff --git a/media/filters/ffmpeg_audio_decoder.cc b/media/filters/ffmpeg_audio_decoder.cc
index 133e7dc9e694852d4e76804c13aac712610ec9d9..827b0bc8805067d8a758eaca88cab292ea0fb141 100644
--- a/media/filters/ffmpeg_audio_decoder.cc
+++ b/media/filters/ffmpeg_audio_decoder.cc
@@ -157,7 +157,7 @@ static void ConvertAudioF32ToS32(void* buffer, int buffer_size) {
 void FFmpegAudioDecoder::DoDecode(Buffer* input) {
   // FFmpeg tends to seek Ogg audio streams in the middle of nowhere, giving us
   // a whole bunch of AV_NOPTS_VALUE packets.  Discard them until we find
-  // something valid.
+  // something valid.  Refer to http://crbug.com/49709
   // TODO(hclam): remove this once fixing the issue in FFmpeg.
   if (input->GetTimestamp() == StreamSample::kInvalidTimestamp &&
       estimated_next_timestamp_ == StreamSample::kInvalidTimestamp &&