Fix seeking when the start time is non-zero.

media/filters/ffmpeg_demuxer.h

Index: media/filters/ffmpeg_demuxer.h
diff --git a/media/filters/ffmpeg_demuxer.h b/media/filters/ffmpeg_demuxer.h
index 02682bbc8b2c38c4b3a07771a7c86558c595bfb9..ebea927b9fda10281cf767557d3bd0b2c0c5c4ab 100644
--- a/media/filters/ffmpeg_demuxer.h
+++ b/media/filters/ffmpeg_demuxer.h
@@ -74,8 +74,7 @@ class FFmpegDemuxerStream : public DemuxerStream {
   // Empties the queues and ignores any additional calls to Read().
   void Stop();
 
-  // Returns the duration of this stream.
-  base::TimeDelta duration();
+  base::TimeDelta duration() const { return duration_; }
 
   // DemuxerStream implementation.
   virtual Type type() OVERRIDE;
@@ -104,6 +103,12 @@ class FFmpegDemuxerStream : public DemuxerStream {
   // Returns an empty string if the key is not present.
   std::string GetMetadata(const char* key) const;
 
+  // Tells the DemuxerStream that all packets with negative timestamps should be
+  // marked for post-decode discard.
+  void enable_negative_timestamp_discard() {
+    discard_negative_timestamps_ = true;
+  }
+
  private:
   friend class FFmpegDemuxerTest;
 
@@ -136,6 +141,7 @@ class FFmpegDemuxerStream : public DemuxerStream {
   bool bitstream_converter_enabled_;
 
   std::string encryption_key_id_;
+  bool discard_negative_timestamps_;
 
   DISALLOW_COPY_AND_ASSIGN(FFmpegDemuxerStream);
 };
@@ -155,7 +161,6 @@ class MEDIA_EXPORT FFmpegDemuxer : public Demuxer {
   virtual void Stop(const base::Closure& callback) OVERRIDE;
   virtual void Seek(base::TimeDelta time, const PipelineStatusCB& cb) OVERRIDE;
   virtual DemuxerStream* GetStream(DemuxerStream::Type type) OVERRIDE;
-  virtual base::TimeDelta GetStartTime() const OVERRIDE;
   virtual base::Time GetTimelineOffset() const OVERRIDE;
   virtual Liveness GetLiveness() const OVERRIDE;
 
@@ -168,6 +173,10 @@ class MEDIA_EXPORT FFmpegDemuxer : public Demuxer {
   void NotifyCapacityAvailable();
   void NotifyBufferingChanged();
 
+  // The lowest demuxed timestamp.  DemuxerStream's must use this to adjust
+  // packet timestamps such that external clients see a zero-based timeline.
+  base::TimeDelta start_time() const { return start_time_; }
+
  private:
   // To allow tests access to privates.
   friend class FFmpegDemuxerTest;
@@ -245,9 +254,9 @@ class MEDIA_EXPORT FFmpegDemuxer : public Demuxer {
   // Derived bitrate after initialization has completed.
   int bitrate_;
 
-  // The first timestamp of the opened media file. This is used to set the
-  // starting clock value to match the timestamps in the media file. Default
-  // is 0.
+  // The first timestamp of the audio or video stream, whichever is lower.  This
+  // is used to adjust timestamps so that external consumers always see a zero
+  // based timeline.
   base::TimeDelta start_time_;
 
   // The Time associated with timestamp 0. Set to a null
@@ -270,6 +279,10 @@ class MEDIA_EXPORT FFmpegDemuxer : public Demuxer {
 
   const NeedKeyCB need_key_cb_;
 
+  // The index of the stream in |streams_| to use for seeking.  Chosen by the
+  // stream with the lowest starting timestamp.
+  int stream_index_for_seeking_;
+
   // NOTE: Weak pointers must be invalidated before all other member variables.
   base::WeakPtrFactory<FFmpegDemuxer> weak_factory_;