This approach potentially breaks uploading function on some installations:

18dd668#diff-d4df0d37ced3953a0c6983e39888b22a

refs.

• https://wordpress.org/support/topic/error-after-updating-29/
• https://wordpress.org/support/topic/admin-ajax-php-errors-cannot-upload-or-search-media-library/

Need to refactor it so that it only active when CHUNK_SIZE const is defined. Otherwise, need to use old uploading method.