Sharepoint 2013 Online CORS Cross Origin Resource Sharing

Question

Sharepoint 2013 Online CORS Cross Origin Resource Sharing

I am trying to implement a simple Sharepoint 2013 Online solution to allow sharepoint to render an external source inside an iframe, the external source in this case is OWA. Placing a simple page renderer does not work because SHAREPOINT does not allow this because it sets the X-Frame-Options 'to' SAMEORIGIN. So I am trying to get around it with simple Javascript in order to modify the HttpHeader sent to the server. This is my code:

<HTML>
<head>
 <script>
 var xhr = new XMLHttpRequest();
 xhr.open("get", "https://xxx.sharepoint.com/sites/dw-local/luca-pappallardo/SitePages/OWAgsfn.aspx", true);
 xhr.onload = function(){
 xhr.setRequestHeader("X-FRAME-OPTION", "ALLOWALL");
};
xhr.send(null);
 </script>
</head>
<body>
 <iframe src="https://outlook.office365.com/owa"></iframe>
</body>
</html>