How can I enable standard zoom controls in a chrome app (extension)?

Question

I would like to be able to zoom in a chrome application (ctrl + scroll, CTRL and +/-, Pinch-zoom). This works when running as a normal webpage but doesn't when running as a chrome app. Is there a way to turn it on?

The Android WebView supports this via code like the following:

    webView.getSettings().setSupportZoom(true);
    webView.getSettings().setBuiltInZoomControls(true);
    webView.getSettings().setDisplayZoomControls(false);

Is there an equivalent for a Chrome App written in JavaScript for ChromeOS?