WP_Http_Encoding::accept_encoding( string $url, array $args )

	public static function accept_encoding( $url, $args ) {
		$type = array();
		$compression_enabled = self::is_available();

		if ( ! $args['decompress'] ) // Decompression specifically disabled.
			$compression_enabled = false;
		elseif ( $args['stream'] ) // Disable when streaming to file.
			$compression_enabled = false;
		elseif ( isset( $args['limit_response_size'] ) ) // If only partial content is being requested, we won't be able to decompress it.
			$compression_enabled = false;

		if ( $compression_enabled ) {
			if ( function_exists( 'gzinflate' ) )
				$type[] = 'deflate;q=1.0';

			if ( function_exists( 'gzuncompress' ) )
				$type[] = 'compress;q=0.5';

			if ( function_exists( 'gzdecode' ) )
				$type[] = 'gzip;q=0.5';
		}

		/**
		 * Filters the allowed encoding types.
		 *
		 * @since WP-3.6.0
		 *
		 * @param array  $type Encoding types allowed. Accepts 'gzinflate',
		 *                     'gzuncompress', 'gzdecode'.
		 * @param string $url  URL of the HTTP request.
		 * @param array  $args HTTP request arguments.
		 */
		$type = apply_filters( 'wp_http_accept_encoding', $type, $url, $args );

		return implode(', ', $type);
	}