Revert of Fix seeking when the start time is non-zero.

media/filters/ffmpeg_audio_decoder.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/ffmpeg_audio_decoder.h"
 
 #include "base/callback_helpers.h"
 #include "base/single_thread_task_runner.h"
 #include "media/base/audio_buffer.h"
 #include "media/base/audio_bus.h"
@@ skipping 231 matching lines @@
   //     Any time Reset() is called.
 
   // Make sure we are notified if http://crbug.com/49709 returns.  Issue also
   // occurs with some damaged files.
   if (!buffer->end_of_stream() && buffer->timestamp() == kNoTimestamp()) {
     DVLOG(1) << "Received a buffer without timestamps!";
     decode_cb.Run(kDecodeError);
     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);
+  }
+
   if (!FFmpegDecode(buffer)) {
     state_ = kError;
     decode_cb.Run(kDecodeError);
     return;
   }
 
   if (buffer->end_of_stream()) {
     state_ = kDecodeFinished;
     output_cb_.Run(AudioBuffer::CreateEOSBuffer());
   }
@@ skipping 153 matching lines @@
 
   ResetTimestampState();
   return true;
 }
 
 void FFmpegAudioDecoder::ResetTimestampState() {
   discard_helper_->Reset(config_.codec_delay());
 }
 
 }  // namespace media