inject.js

song = "";
setInterval(function() {
	if (song != $('#track-name').find('a').text().replace(/ /g, "~") + '|' + $('#track-artist > a').text().replace(/ /g, "~")) {
		song = $('#track-name').find('a').text().replace(/ /g, "~") + '|' + $('#track-artist > a').text().replace(/ /g, "~");
		$.ajax({
			//The URL to process the request
			'url': 'https://your.webserver/relay.php?m=' + song,
			'type': 'GET',
			'success': function(data) {
				if (data == "success") {
					console.log('request sent!');
				}
			}
		});
		console.log(song);
	}
}, 2000);