If splitting of data transfer is enabled this callback is called after
download of an individual chunk finished.
Note! After this callback was set then it have to be called FOR ALL chunks.
Even if downloading of this chunk was skipped in CHUNK_BGN_FUNC.
This is the reason why we don't need "transfer_info" parameter in this
callback and we are not interested in "remains" parameter too.
If splitting of data transfer is enabled this callback is called after download of an individual chunk finished. Note! After this callback was set then it have to be called FOR ALL chunks. Even if downloading of this chunk was skipped in CHUNK_BGN_FUNC. This is the reason why we don't need "transfer_info" parameter in this callback and we are not interested in "remains" parameter too.