We can get the content size and the window size, but not the chrome position.

At the moment we do this:

```
leftBorderWidth = (windowWidth - contentWidth) / 2;
titlebarHeight = windowHeight - (contentHeight + leftBorderWidth);
```

which makes some assumptions so therefore feels a bit wrong.

it would be nice if alongside getContentSize (https://github.com/electron/electron/blob/master/docs/api/browser-window.md#wingetcontentsize) there was a getContentOffset.

I've been looking at the C++ - https://github.com/electron/electron/blob/e05804848f98959d63337aacd9047cd579c5b23f/chromium_src/extensions/browser/app_window/size_constraints.cc and I don't see an easy way to get this information - do you have any ideas or pointers if you accept this as a feature request?

atom/browser/native_window.cc
const std::vector<DraggableRegion>& regions) {
  
  if (has_frame_)
    return;
  draggable_region_ = DraggableRegionsToSkRegion(regions);
}
void NativeWindow::ScheduleUnresponsiveEvent(int ms) {
  if (!window_unresposive_closure_.IsCancelled())
    return;
  window_unresposive_closure_.Reset(
      base::Bind(&NativeWindow::NotifyWindowUnresponsive,
                 weak_factory_.GetWeakPtr()));
  base::MessageLoop::current()->PostDelayedTask(
      FROM_HERE,
      window_unresposive_closure_.callback(),
      base::TimeDelta::FromMilliseconds(ms));
}
void NativeWindow::NotifyWindowUnresponsive() {
  window_unresposive_closure_.Cancel();
  if (!is_closed_ && !IsUnresponsiveEventSuppressed() && IsEnabled())
    FOR_EACH_OBSERVER(NativeWindowObserver,
                      observers_,
                      OnRendererUnresponsive());
}
void NativeWindow::NotifyReadyToShow() {
  FOR_EACH_OBSERVER(NativeWindowObserver, observers_, OnReadyToShow());
}
}