Make VideoDecoder use (kAborted, NULL) to signify an aborted decode, instead of (kOk, NULL).

media/base/video_decoder.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MEDIA_BASE_VIDEO_DECODER_H_
 #define MEDIA_BASE_VIDEO_DECODER_H_
 
 #include "base/callback.h"
 #include "base/memory/ref_counted.h"
 #include "media/base/media_export.h"
 #include "media/base/pipeline_status.h"
 #include "ui/gfx/size.h"
 
 namespace media {
 
 class DecoderBuffer;
 class VideoDecoderConfig;
 class VideoFrame;
 
 class MEDIA_EXPORT VideoDecoder {
  public:
   // Status codes for decode operations on VideoDecoder.
   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.
   };
 
   VideoDecoder();
   virtual ~VideoDecoder();
 
   // Initializes a VideoDecoder with the given |config|, executing the
   // |status_cb| upon completion.
@@ skipping 10 matching lines @@
   // Requests a |buffer| to be decoded. The status of the decoder and decoded
   // frame are returned via the provided callback. Only one decode may be in
   // flight at any given time.
   //
   // Implementations guarantee that the callback will not be called from within
   // this method.
   //
   // If the returned status is kOk:
   // - Non-EOS (end of stream) frame contains decoded video data.
   // - EOS frame indicates the end of the stream.
-  // - NULL frame indicates an aborted decode. This can happen if Reset() or
-  //   Stop() is called during the decoding process.
   // 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, 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.
@@ skipping 20 matching lines @@
   // use a fixed set of VideoFrames for decoding.
   virtual bool CanReadWithoutStalling() const;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(VideoDecoder);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_VIDEO_DECODER_H_