Change IAudioTrackCallback buffer return values

    class IAudioTrackCallback : public virtual RefBase {

      friend AudioTrack;

      protected:

        // Request to write more data to buffer.

        // This event only occurs for TRANSFER_CALLBACK.

        // If this event is delivered but the callback handler does not want to write more data,

        // the handler must ignore the event by returning zero.

        // This might occur, for example, if the application is waiting for source data or is at

        // the end of stream.

        // For data filling, it is preferred that the callback does not block and instead returns

        // a short count of the amount of data actually delivered.

        // buffer: Buffer to fill

        virtual size_t onMoreData(const AudioTrack::Buffer& buffer) { return buffer.size; }

       /* Request to write more data to buffer.

        * This event only occurs for TRANSFER_CALLBACK.

        * If this event is delivered but the callback handler does not want to write more data,

        * the handler must ignore the event by returning zero.

        * This might occur, for example, if the application is waiting for source data or is at

        * the end of stream.

        * For data filling, it is preferred that the callback does not block and instead returns

        * a short count of the amount of data actually delivered.

        * Parameters:

        *  - buffer: Buffer to fill

        * Returns:

        * Amount of data actually written in bytes.

        */

        virtual size_t onMoreData([[maybe_unused]] const AudioTrack::Buffer& buffer) { return 0; }

        // Buffer underrun occurred. This will not occur for static tracks.

        virtual void onUnderrun() {}

        // Sample loop end was reached; playback restarted from loop start if loop count was not 0

        // for a static track.

        // loopsRemaining: Number of loops remaining to be played. -1 if infinite looping.

       /* Sample loop end was reached; playback restarted from loop start if loop count was not 0

        * for a static track.

        * Parameters:

        *  - loopsRemaining: Number of loops remaining to be played. -1 if infinite looping.

        */

        virtual void onLoopEnd([[maybe_unused]] int32_t loopsRemaining) {}

        // Playback head is at the specified marker (See setMarkerPosition()).

        // onMarker: Marker position in frames

       /* Playback head is at the specified marker (See setMarkerPosition()).

        * Parameters:

        *  - onMarker: Marker position in frames

        */

        virtual void onMarker([[maybe_unused]] uint32_t markerPosition) {}

        // Playback head is at a new position (See setPositionUpdatePeriod()).

        // newPos: New position in frames

       /* Playback head is at a new position (See setPositionUpdatePeriod()).

        * Parameters:

        *  - newPos: New position in frames

        */

        virtual void onNewPos([[maybe_unused]] uint32_t newPos) {}

        // Playback has completed for a static track.

        virtual void onBufferEnd() {}

        // IAudioTrack was re-created, either due to re-routing and voluntary invalidation

        // by mediaserver, or mediaserver crash.

        virtual void onNewIAudioTrack() {}

        // Sent after all the buffers queued in AF and HW are played back (after stop is called)

        // for an offloaded track.

        virtual void onStreamEnd() {}

        // Delivered periodically and when there's a significant change

        // in the mapping from frame position to presentation time.

        // See AudioTimestamp for the information included with event.

        // TODO not yet implemented.

       /* Delivered periodically and when there's a significant change

        * in the mapping from frame position to presentation time.

        * See AudioTimestamp for the information included with event.

        * TODO not yet implemented.

        * Parameters:

        *  - timestamp: New frame position and presentation time mapping.

        */

        virtual void onNewTimestamp([[maybe_unused]] AudioTimestamp timestamp) {}

        // Notification that more data can be given by write()

        // This event only occurs for TRANSFER_SYNC_NOTIF_CALLBACK.

        // Similar to onMoreData(), return the number of frames actually written

        // buffer: Buffer to fill

        virtual size_t onCanWriteMoreData(const AudioTrack::Buffer& buffer) { return buffer.size; }

       /* Notification that more data can be given by write()

        * This event only occurs for TRANSFER_SYNC_NOTIF_CALLBACK.

        * Similar to onMoreData(), return the number of frames actually written

        * Parameters:

        *  - buffer: Buffer to fill

        * Returns:

        * Amount of data actually written in bytes.

        */

        virtual size_t onCanWriteMoreData([[maybe_unused]] const AudioTrack::Buffer& buffer) {

            return 0;

        }

    };

    /* Returns the minimum frame count required for the successful creation of