media: Reland "Simplify {Audio|Video}Decoder initialization callback."

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 <string>
 
 #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/geometry/size.h"
 
 namespace media {
 
 class DecoderBuffer;
 class VideoDecoderConfig;
 class VideoFrame;
 
 class MEDIA_EXPORT VideoDecoder {
  public:
   // Status codes for decode operations on VideoDecoder.
   // TODO(rileya): Now that both AudioDecoder and VideoDecoder Status enums
   // match, break them into a decoder_status.h.
   enum Status {
-    kOk,  // Everything went as planned.
-    kAborted,  // Decode was aborted as a result of Reset() being called.
+    kOk,          // Everything went as planned.
+    kAborted,     // Decode was aborted as a result of Reset() being called.
     kDecodeError  // Decoding error happened.
   };
 
+  // Callback for VideoDecoder initialization.
+  typedef base::Callback<void(bool success)> InitCB;
+
   // Callback for VideoDecoder to return a decoded frame whenever it becomes
   // available. Only non-EOS frames should be returned via this callback.
   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();
 
   // Fires any pending callbacks, stops and destroys the decoder.
   // Note: Since this is a destructor, |this| will be destroyed after this call.
   // Make sure the callbacks fired from this call doesn't post any task that
   // depends on |this|.
   virtual ~VideoDecoder();
 
   // Returns the name of the decoder for logging purpose.
   virtual std::string GetDisplayName() const = 0;
 
   // Initializes a VideoDecoder with the given |config|, executing the
-  // |status_cb| upon completion. |output_cb| is called for each output frame
+  // |init_cb| upon completion. |output_cb| is called for each output frame
   // decoded by Decode().
   //
   // If |low_delay| is true then the decoder is not allowed to queue frames,
   // except for out-of-order frames, i.e. if the next frame can be returned it
   // must be returned without waiting for Decode() to be called again.
   // Initialization should fail if |low_delay| is true and the decoder cannot
   // satisfy the requirements above.
   //
   // Note:
   // 1) The VideoDecoder will be reinitialized if it was initialized before.
   //    Upon reinitialization, all internal buffered frames will be dropped.
   // 2) This method should not be called during pending decode or reset.
-  // 3) No VideoDecoder calls should be made before |status_cb| is executed.
+  // 3) No VideoDecoder calls should be made before |init_cb| is executed.
   virtual void Initialize(const VideoDecoderConfig& config,
                           bool low_delay,
-                          const PipelineStatusCB& status_cb,
+                          const InitCB& init_cb,
                           const OutputCB& output_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
   // decoding multiple buffers in parallel. Callers should call
   // GetMaxDecodeRequests() to get number of buffers that may be decoded in
   // parallel. Decoder must call |decode_cb| in the same order in which Decode()
   // is called.
   //
   // Implementations guarantee that the callback will not be called from within
@@ skipping 30 matching lines @@
   // Returns maximum number of parallel decode requests.
   virtual int GetMaxDecodeRequests() const;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(VideoDecoder);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_VIDEO_DECODER_H_