* Electron version: 1.4.14
* Operating system: Windows 8.1

### Expected behavior

A fullscreen transparent window should be transparent.

### Actual behavior

The window is not transparent (has a white background).

### How to reproduce

```
electron.app.on("ready", function () {
    var win = new BrowserWindow({
        show: true,
        frame: false,
        fullscreen: true,
        transparent: true
    });
});
```

Refs https://github.com/electron/electron/issues/8321#issuecomment-273615701


atom/browser/native_window_views.cc
#include "atom/browser/native_window_views.h"
#include <string>
#include <vector>
#include "atom/browser/ui/views/menu_bar.h"
#include "atom/browser/ui/views/menu_layout.h"
#include "atom/browser/window_list.h"
#include "atom/common/color_util.h"
#include "atom/common/draggable_region.h"
#include "atom/common/native_mate_converters/image_converter.h"
#include "atom/common/options_switches.h"
#include "base/strings/utf_string_conversions.h"
#include "brightray/browser/inspectable_web_contents.h"
#include "brightray/browser/inspectable_web_contents_view.h"
#include "content/public/browser/browser_thread.h"
#include "content/public/browser/native_web_keyboard_event.h"
#include "native_mate/dictionary.h"
#include "ui/aura/window_tree_host.h"
#include "ui/base/hit_test.h"
#include "ui/gfx/image/image.h"
#include "ui/views/background.h"
#include "ui/views/controls/webview/unhandled_keyboard_event_handler.h"
#include "ui/views/controls/webview/webview.h"