call from javascript using chrome extension

The Chrome extension works great, but I need to run a function before dialing the number from my website. Like:

<button type='button' onclick=makecall('".$result->PHONE."')>".$result->PHONE."</button>

<script>

function makecall($number){

alert("tel:"+thenumber);

window.location.href("tel:"+$number);

}

</script>

Is there a function in the chrome extension I can call to send the number to the dialer?