Fix seeking when the start time is non-zero.

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 704eefde5f3b84d76253688572b2a222c9f88ddf..0cd07123e1ca5a2a27eb75c3c3c9bea5cc7d1f64 100644
--- a/media/filters/ffmpeg_audio_decoder.cc
+++ b/media/filters/ffmpeg_audio_decoder.cc
@@ -261,16 +261,6 @@ void FFmpegAudioDecoder::DecodeBuffer(
     return;
   }
 
-  if (!buffer->end_of_stream() && !discard_helper_->initialized() &&
-      codec_context_->codec_id == AV_CODEC_ID_VORBIS &&
-      buffer->timestamp() < base::TimeDelta()) {
-    // Dropping frames for negative timestamps as outlined in section A.2
-    // in the Vorbis spec. http://xiph.org/vorbis/doc/Vorbis_I_spec.html
-    const int discard_frames =
-        discard_helper_->TimeDeltaToFrames(-buffer->timestamp());
-    discard_helper_->Reset(discard_frames);
-  }
-
   // Transition to kFlushCodec on the first end of stream buffer.
   if (state_ == kNormal && buffer->end_of_stream()) {
     state_ = kFlushCodec;