Revert 276344 "Add callback in VideoDecoder and AudioDecoder to ..."

media/base/video_decoder.h

Index: media/base/video_decoder.h
===================================================================
--- media/base/video_decoder.h	(revision 277175)
+++ media/base/video_decoder.h	(working copy)
@@ -25,24 +25,16 @@
   enum Status {
     kOk,  // Everything went as planned.
     kAborted,  // Decode was aborted as a result of Reset() being called.
+    kNotEnoughData,  // Not enough data to produce a video frame.
     kDecodeError,  // Decoding error happened.
     kDecryptError  // Decrypting error happened.
   };
 
-  // Callback to return decode frames.
-  typedef base::Callback<void(const scoped_refptr<VideoFrame>&)> OutputCB;
-
-  // Callback type for Decode(). Called after the decoder has completed decoding
-  // corresponding DecoderBuffer, indicating that it's ready to accept another
-  // buffer to decode.
-  typedef base::Callback<void(Status status)> DecodeCB;
-
   VideoDecoder();
   virtual ~VideoDecoder();
 
   // Initializes a VideoDecoder with the given |config|, executing the
-  // |status_cb| upon completion. |output_cb| is called for each output frame
-  // decoded by Decode().
+  // |status_cb| upon completion.
   //
   // Note:
   // 1) The VideoDecoder will be reinitialized if it was initialized before.
@@ -52,8 +44,7 @@
   //    |status_cb| is executed.
   virtual void Initialize(const VideoDecoderConfig& config,
                           bool low_delay,
-                          const PipelineStatusCB& status_cb,
-                          const OutputCB& output_cb) = 0;
+                          const PipelineStatusCB& status_cb) = 0;
 
   // Requests a |buffer| to be decoded. The status of the decoder and decoded
   // frame are returned via the provided callback. Some decoders may allow
@@ -67,18 +58,25 @@
   // Decode() calls (i.e. |decode_cb| will be called even Decode() is never
   // called again).
   //
-  // After decoding is finished the decoder calls |output_cb| specified in
-  // Initialize() for each decoded frame. |output_cb| may be called before or
-  // after |decode_cb|.
-  //
-  // If |buffer| is an EOS buffer then the decoder must be flushed, i.e.
-  // |output_cb| must be called for each frame pending in the queue and
-  // |decode_cb| must be called after that.
+  // If the returned status is kOk:
+  // - Non-EOS (end of stream) frame contains decoded video data.
+  // - EOS frame indicates the end of the stream.
+  // Otherwise the returned frame must be NULL.
+  typedef base::Callback<void(Status,
+                              const scoped_refptr<VideoFrame>&)> DecodeCB;
   virtual void Decode(const scoped_refptr<DecoderBuffer>& buffer,
                       const DecodeCB& decode_cb) = 0;
 
-  // Resets decoder state. All pending Decode() requests will be finished or
-  // aborted before |closure| is called.
+  // Some VideoDecoders may queue up multiple VideoFrames from a single
+  // DecoderBuffer, if we have any such queued frames this will return the next
+  // one. Otherwise we return a NULL VideoFrame.
+  //
+  // TODO(xhwang): Revisit this method.
+  virtual scoped_refptr<VideoFrame> GetDecodeOutput();
+
+  // Resets decoder state, fulfilling all pending DecodeCB and dropping extra
+  // queued decoded data. After this call, the decoder is back to an initialized
+  // clean state.
   // Note: No VideoDecoder calls should be made before |closure| is executed.
   virtual void Reset(const base::Closure& closure) = 0;