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
void Maximize() override;
  void Unmaximize() override;
  bool IsMaximized() override;
  void Minimize() override;
  void Restore() override;
  bool IsMinimized() override;
  void SetFullScreen(bool fullscreen) override;
  bool IsFullscreen() const override;
  void SetBounds(const gfx::Rect& bounds, bool animate) override;
  gfx::Rect GetBounds() override;
  gfx::Size GetContentSize() override;
  void SetContentSizeConstraints(
      const extensions::SizeConstraints& size_constraints) override;
  void SetResizable(bool resizable) override;
  bool IsResizable() override;
  void SetMovable(bool movable) override;
  bool IsMovable() override;
  void SetMinimizable(bool minimizable) override;
  bool IsMinimizable() override;
  void SetMaximizable(bool maximizable) override;
  bool IsMaximizable() override;
  void SetFullScreenable(bool fullscreenable) override;
  bool IsFullScreenable() override;
  void SetClosable(bool closable) override;
  bool IsClosable() override;
  void SetAlwaysOnTop(bool top) override;
  bool IsAlwaysOnTop() override;
  void Center() override;
  void SetTitle(const std::string& title) override;
  std::string GetTitle() override;