main.js

var app = require('app');
var BrowserWindow = require('browser-window');

app.on('window-all-closed', function() {
    app.quit();
});

app.on('ready', function() {
  new BrowserWindow({width: 1024, height: 600})
  .loadUrl('http://mozilla.github.io/pdf.js/web/viewer.html')
});

package.json

{
  "main": "main.js"
}