* Electron version:
1.7.0+  (it works in 1.6.15)
* Operating system:
Windows 10 x64

### Expected behavior
When passing in a screen id getUserMedia should return a stream for the corresponding screen.

### Actual behavior
When passing in a screen id getUserMedia returns a stream from a different screen, or a broken stream in some situations.

** means primary monitor

Monitor configuration and results: 
- [ 1**, 2 ] - Capturing either screen works
- [ 1, 2** ] - Capturing screen 1 returns a stream for screen 2, capturing screen 2 returns a broken stream
- [ 2, 1** ] - Capturing screen 1 works, capturing screen 2 returns a broken stream.
- [ 2**, 1 ] - capturing screen 1 returns a stream for screen 2, capturing screen 2 returns stream for screen 1.

### How to reproduce

If you provide a URL, please list the commands required to clone/setup/run your repo e.g.
```bash
git clone https://github.com/hokein/electron-screen-recorder.git
cd electron-screen-recorder
npm install
npm uninstall electron-prebuilt --save-dev
npm install electron@1.7.10 --save
./node_modules/.bin/electron .
```
Attempt one of the broken configurations above to see results.

  
atom/browser/api/atom_api_desktop_capturer.cc
bool capture_screen,
                                    const gfx::Size& thumbnail_size) {
  webrtc::DesktopCaptureOptions options =
      webrtc::DesktopCaptureOptions::CreateDefault();
#if defined(OS_WIN)
  
  
  
  
  
  
  options.set_disable_effects(false);
#endif
  std::unique_ptr<webrtc::DesktopCapturer> screen_capturer(
      capture_screen ? webrtc::DesktopCapturer::CreateScreenCapturer(options)
                     : nullptr);
  std::unique_ptr<webrtc::DesktopCapturer> window_capturer(
      capture_window ? webrtc::DesktopCapturer::CreateWindowCapturer(options)
                     : nullptr);
  media_list_.reset(new NativeDesktopMediaList(
      std::move(screen_capturer), std::move(window_capturer)));
  media_list_->SetThumbnailSize(thumbnail_size);
  media_list_->StartUpdating(this);
}
void DesktopCapturer::OnSourceAdded(int index) {
}
void DesktopCapturer::OnSourceRemoved(int index) {
}
void DesktopCapturer::OnSourceMoved(int old_index, int new_index) {