Convert Filter::Seek() to use new callback system.

media/filters/video_renderer_base.h

Index: media/filters/video_renderer_base.h
diff --git a/media/filters/video_renderer_base.h b/media/filters/video_renderer_base.h
index 66eba6e8894a0ba759c6d7834c403e7826c29275..6a9a97e607b8d65629970a621b00924493e310bf 100644
--- a/media/filters/video_renderer_base.h
+++ b/media/filters/video_renderer_base.h
@@ -51,7 +51,7 @@ class VideoRendererBase : public VideoRenderer,
   virtual void Flush(FilterCallback* callback);
   virtual void Stop(FilterCallback* callback);
   virtual void SetPlaybackRate(float playback_rate);
-  virtual void Seek(base::TimeDelta time, FilterCallback* callback);
+  virtual void Seek(base::TimeDelta time, const FilterStatusCB& cb);
 
   // VideoRenderer implementation.
   virtual void Initialize(VideoDecoder* decoder,
@@ -213,7 +213,7 @@ class VideoRendererBase : public VideoRenderer,
 
   // Filter callbacks.
   scoped_ptr<FilterCallback> flush_callback_;
-  scoped_ptr<FilterCallback> seek_callback_;
+  FilterStatusCB seek_cb_;
   scoped_ptr<StatisticsCallback> statistics_callback_;
 
   base::TimeDelta seek_timestamp_;