Available space in chromebook for the current profile

[Gaurav]

We are using the below snippet from https://developer.chrome.com/apps/offline_storage to get the available space on chromebook device. We are using "unlimitedStorage" in manifest file. But on ChrmeBook this is giving us the available space for the entire device and not for the current user profile, what we need is an API/Code which gives us similar results to chrome://quota-internals/

navigator.webkitTemporaryStorage.queryUsageAndQuota ( 
function(usedBytes, grantedBytes) {  
    console.log('we are using ', usedBytes, ' of ', grantedBytes, 'bytes');
}, 
function(e) { console.log('Error', e);  }

Even tried with the chrome.system.storage.getInfo but on chromebook it returns empty array.