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
ScheduleUnresponsiveEvent(50);
}
void NativeWindow::RendererResponsive(content::WebContents* source) {
  window_unresposive_closure_.Cancel();
  FOR_EACH_OBSERVER(NativeWindowObserver, observers_, OnRendererResponsive());
}
void NativeWindow::NotifyWindowClosed() {
  if (is_closed_)
    return;
  WindowList::RemoveWindow(this);
  is_closed_ = true;
  FOR_EACH_OBSERVER(NativeWindowObserver, observers_, OnWindowClosed());
}
void NativeWindow::NotifyWindowBlur() {
  FOR_EACH_OBSERVER(NativeWindowObserver, observers_, OnWindowBlur());
}
void NativeWindow::NotifyWindowFocus() {
  FOR_EACH_OBSERVER(NativeWindowObserver, observers_, OnWindowFocus());
}
void NativeWindow::NotifyWindowShow() {
  FOR_EACH_OBSERVER(NativeWindowObserver, observers_, OnWindowShow());
}
void NativeWindow::NotifyWindowHide() {