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/api/atom_api_window.h
#if defined(OS_WIN)
  void OnWindowMessage(UINT message, WPARAM w_param, LPARAM l_param) override;
  #endif
 private:
  
  void Close();
  void Focus();
  void Blur();
  bool IsFocused();
  void Show();
  void ShowInactive();
  void Hide();
  bool IsVisible();
  bool IsEnabled();
  void Maximize();
  void Unmaximize();
  bool IsMaximized();
  void Minimize();
  void Restore();
  bool IsMinimized();
  void SetFullScreen(bool fullscreen);
  bool IsFullscreen();
  void SetBounds(const gfx::Rect& bounds, mate::Arguments* args);
  gfx::Rect GetBounds();
  void SetSize(int width, int height, mate::Arguments* args);
  std::vector<int> GetSize();
  void SetContentSize(int width, int height, mate::Arguments* args);
  std::vector<int> GetContentSize();
  void SetMinimumSize(int width, int height);
  std::vector<int> GetMinimumSize();