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
void SetMaximumSize(int width, int height);
  std::vector<int> GetMaximumSize();
  void SetSheetOffset(double offsetY, mate::Arguments* args);
  void SetResizable(bool resizable);
  bool IsResizable();
  void SetMovable(bool movable);
  bool IsMovable();
  void SetMinimizable(bool minimizable);
  bool IsMinimizable();
  void SetMaximizable(bool maximizable);
  bool IsMaximizable();
  void SetFullScreenable(bool fullscreenable);
  bool IsFullScreenable();
  void SetClosable(bool closable);
  bool IsClosable();
  void SetAlwaysOnTop(bool top);
  bool IsAlwaysOnTop();
  void Center();
  void SetPosition(int x, int y, mate::Arguments* args);
  std::vector<int> GetPosition();
  void SetTitle(const std::string& title);
  std::string GetTitle();
  void FlashFrame(bool flash);
  void SetSkipTaskbar(bool skip);
  void SetKiosk(bool kiosk);
  bool IsKiosk();
  void SetBackgroundColor(const std::string& color_name);
  void SetHasShadow(bool has_shadow);
  bool HasShadow();
  void FocusOnWebView();