media: Support better decoder switching

media/filters/decoder_stream.h

Index: media/filters/decoder_stream.h
diff --git a/media/filters/decoder_stream.h b/media/filters/decoder_stream.h
index 0056269389290bcec15ae01cfe81af0cf3e59bb5..b3d4eb0e3e41fc8831e44fdf0ab8aca4e2da22ba 100644
--- a/media/filters/decoder_stream.h
+++ b/media/filters/decoder_stream.h
@@ -50,16 +50,18 @@ class MEDIA_EXPORT DecoderStream {
     DECODE_ERROR,  // Decoder returned decode error.
   };
 
+  // Callback to create a list of decoders.
+  using CreateDecodersCB = base::RepeatingCallback<ScopedVector<Decoder>()>;
+
   // Indicates completion of a DecoderStream initialization.
-  typedef base::Callback<void(bool success)> InitCB;
+  using InitCB = base::Callback<void(bool success)>;
 
   // Indicates completion of a DecoderStream read.
-  typedef base::Callback<void(Status, const scoped_refptr<Output>&)> ReadCB;
+  using ReadCB = base::Callback<void(Status, const scoped_refptr<Output>&)>;
 
-  DecoderStream(
-      const scoped_refptr<base::SingleThreadTaskRunner>& task_runner,
-      ScopedVector<Decoder> decoders,
-      const scoped_refptr<MediaLog>& media_log);
+  DecoderStream(const scoped_refptr<base::SingleThreadTaskRunner>& task_runner,
+                const CreateDecodersCB& create_decoders_cb,
+                const scoped_refptr<MediaLog>& media_log);
   virtual ~DecoderStream();
 
   // Returns the string representation of the StreamType for logging purpose.