Uncaught TypeError: Cannot read property 'onLaunched' of undefined

{
"name": "Hello World!",
"description": "My first packaged app.",
"manifest_version": 2,

"version": "0.1",
"app": {
    "background": {
        "scripts": ["background.js"]
    }
},
"icons": {
    "16": "calculator-16.png",
    "128": "calculator-128.png"
}

chrome.app.runtime.onLaunched.addListener(function() {
    chrome.app.window.create('window.html', {
        'width': 400,
        'height': 500
    });
});