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.cc
.SetMethod("isEnabled", &Window::IsEnabled)
      .SetMethod("maximize", &Window::Maximize)
      .SetMethod("unmaximize", &Window::Unmaximize)
      .SetMethod("isMaximized", &Window::IsMaximized)
      .SetMethod("minimize", &Window::Minimize)
      .SetMethod("restore", &Window::Restore)
      .SetMethod("isMinimized", &Window::IsMinimized)
      .SetMethod("setFullScreen", &Window::SetFullScreen)
      .SetMethod("isFullScreen", &Window::IsFullscreen)
      .SetMethod("setAspectRatio", &Window::SetAspectRatio)
#if !defined(OS_WIN)
      .SetMethod("setParentWindow", &Window::SetParentWindow)
#endif
      .SetMethod("getParentWindow", &Window::GetParentWindow)
      .SetMethod("getChildWindows", &Window::GetChildWindows)
      .SetMethod("isModal", &Window::IsModal)
      .SetMethod("getNativeWindowHandle", &Window::GetNativeWindowHandle)
      .SetMethod("getBounds", &Window::GetBounds)
      .SetMethod("setBounds", &Window::SetBounds)
      .SetMethod("getSize", &Window::GetSize)
      .SetMethod("setSize", &Window::SetSize)
      .SetMethod("getContentSize", &Window::GetContentSize)
      .SetMethod("setContentSize", &Window::SetContentSize)
      .SetMethod("setMinimumSize", &Window::SetMinimumSize)
      .SetMethod("getMinimumSize", &Window::GetMinimumSize)
      .SetMethod("setMaximumSize", &Window::SetMaximumSize)
      .SetMethod("getMaximumSize", &Window::GetMaximumSize)
      .SetMethod("setSheetOffset", &Window::SetSheetOffset)
      .SetMethod("setResizable", &Window::SetResizable)
      .SetMethod("isResizable", &Window::IsResizable)