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
return aspect_ratio_extraSize_;
}
void NativeWindow::SetAspectRatio(double aspect_ratio,
                                  const gfx::Size& extra_size) {
  aspect_ratio_ = aspect_ratio;
  aspect_ratio_extraSize_ = extra_size;
}
void NativeWindow::RequestToClosePage() {
  bool prevent_default = false;
  FOR_EACH_OBSERVER(NativeWindowObserver,
                    observers_,
                    WillCloseWindow(&prevent_default));
  if (prevent_default) {
    WindowList::WindowCloseCancelled(this);
    return;
  }
  
  
  
  
  if (window_unresposive_closure_.IsCancelled())
    ScheduleUnresponsiveEvent(5000);
  if (web_contents()->NeedToFireBeforeUnload())
    web_contents()->DispatchBeforeUnload();
  else
    web_contents()->Close();
}
void NativeWindow::CloseContents(content::WebContents* source) {