Enable useContentSize BrowserWindow option

From the documentation:



> `useContentSize` Boolean - The `width` and `height` would be used as web

> page’s size, which means the actual window’s size will include window

> frame’s size and be slightly larger. Default is `false`.



The original issue is that when you specify a width/height, the actual

size that you get is slighly smaller, since the OS title bar is included

in the size you provide.



By using the `useContentSize` option, we ensure the `WebView` gets the

intended size, no matter the title bar.



This PR invalidates: https://github.com/resin-io/etcher/pull/244



Signed-off-by: Juan Cruz Viotti <jviottidc@gmail.com>

lib/etcher.js

@@ -38,6 +38,7 @@ electron.app.on('ready', function() {
     mainWindow = new electron.BrowserWindow({
       width: 800,
       height: 380,
+      useContentSize: true,
       show: false,
       resizable: false,
       fullscreen: false,