Chrome Storage Check

storage_check.js

// Request storage usage and capacity left
window.webkitStorageInfo.queryUsageAndQuota(webkitStorageInfo.TEMPORARY, 
//the type can be either TEMPORARY or PERSISTENT
function(used, remaining) {
  console.log("Used quota: " + used + ", remaining quota: " + remaining);
}, function(e) {
  console.log('Error', e); 
} );