media: Introduce Renderer interface and RendererImpl.

content/renderer/media/webmediaplayer_impl.h

Index: content/renderer/media/webmediaplayer_impl.h
diff --git a/content/renderer/media/webmediaplayer_impl.h b/content/renderer/media/webmediaplayer_impl.h
index 522519bf24b1ac777abdfd768339b081a206004a..19cd93ac00a7b46e743f99b0eaceae08d2792d05 100644
--- a/content/renderer/media/webmediaplayer_impl.h
+++ b/content/renderer/media/webmediaplayer_impl.h
@@ -202,6 +202,9 @@ class WebMediaPlayerImpl
   // Called when the data source is downloading or paused.
   void NotifyDownloading(bool is_downloading);
 
+  // Creates a media::Renderer that will be used by the Pipeline.
+  scoped_ptr<media::Renderer> CreateRenderer();
+
   // Finishes starting the pipeline due to a call to load().
   void StartPipeline();