title: how to get the Callback from chrome.runtime.sendMessage in Angular 4?
body: <p>I am really new working with Angular 4 and Chrome Extensions, but I have this code to comunicate my app in Angular with the Chrome extension.</p>
  
  <p>Code in Angular 4.</p>
  
  <pre><code>public myObjectExtension : any;
  
  public getObjectChrome(){
      chrome.runtime.sendMessage(extensionID, 'getObject', function(response) {
          console.log(response);
          this.myObjectExtension = reponse;
    });
  </code></pre>
  
  <p>}</p>
  
  <p>and I have this in my Chrome Extension.</p>
  
  <pre><code>chrome.runtime.onMessageExternal.addListener(
     function(request, sender, sendResponse) {
       if(request == "getObject"){
            sendResponse({
                name: "Afro",
                lastname: "Chase"
            });
       }
  </code></pre>
  
  <p>When I run the application the console log show me correctly the data, like this. </p>
  
  <pre><code>{name: "Afro", lastname: "Chase}
  </code></pre>
  
  <p>but when I pass the value of "reponse" to "this.myObjectExtension", the console shows me this </p>
  
  <pre><code>TypeError: Cannot set property 'myObjectExtension' of undefined
  </code></pre>
  
  <p>I undestand that var "this.myObjectExtension" is not defined inside of the method, but how can I do to retrive the "response" and assign it to my var "this.myObjectExtension"? </p>