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_views.h
class MenuBar;
class WindowStateWatcher;
#if defined(OS_WIN)
class AtomDesktopWindowTreeHostWin;
#elif defined(USE_X11)
class EventDisabler;
#endif
class NativeWindowViews : public NativeWindow,
#if defined(OS_WIN)
                          public MessageHandlerDelegate,
#endif
                          public views::WidgetDelegateView,
                          public views::WidgetObserver {
 public:
  NativeWindowViews(brightray::InspectableWebContents* inspectable_web_contents,
                    const mate::Dictionary& options,
                    NativeWindow* parent);
  ~NativeWindowViews() override;
  
  void Close() override;
  void CloseImmediately() override;
  void Focus(bool focus) override;
  bool IsFocused() override;
  void Show() override;
  void ShowInactive() override;
  void Hide() override;
  bool IsVisible() override;
  bool IsEnabled() override;