Electron pdf viewer

I have an electron app that loads url from php server. And the page contains an iframe having a source to pdf. The page seems absolutely ok in web browser but asks for downlaod in electron app window. any help.

My codes for html page is

==================
<h1>Hello World!</h1>
Some html content here...
<iframe src="http://mozilla.github.io/pdf.js/web/compressed.tracemonkey-pldi-09.pdf" width="1200" height="800"></iframe>

===================

And my js code is something like

mainWindow = new BrowserWindow({width: 800, height: 600})
mainWindow.loadURL(url.format({
pathname: path.join(__dirname, 'index.html'),
protocol: 'file:',
slashes: true
}))

app.on('ready', createWindow)

Any help would be really greatful...

via Hari Babu