Binding for message passing scope in Chrome Extension

Question

I'm trying to follow along with this question, but my code is not working and I cannot figure out why. I'm passing a variable to my content script from a script controlling an iFrame (popup.js), and having the content script respond with the data I need to work with in popup.js. The problem is, I need to be able to work with the data throughout popup.js, and the message passing scope doesn't allow for that, so I am trying to use the bind method as follows:

var currentSite;
chrome.tabs.query({active: true, currentWindow: true}, function(tabs) {
    let bindSite = function(response){
        console.log(response);
        this.currentSite = response.Site;
    };
    chrome.tabs.sendMessage(tabs[0].id, {type: "getSite"}, bindSite.bind(this));
});
console.log("Since I bound it, currentSite should be in the scope here " + currentSite);

The site prints in the console.log() that is inside the function, but it prints undefined in the console.log() statement outside the function. What am I missing?