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
auto buffer = node::Buffer::Copy(isolate, static_cast<char*>(val), size);
  if (buffer.IsEmpty())
    return v8::Null(isolate);
  else
    return buffer.ToLocalChecked();
}
}  
Window::Window(v8::Isolate* isolate, v8::Local<v8::Object> wrapper,
               const mate::Dictionary& options) {
  
  mate::Dictionary web_preferences = mate::Dictionary::CreateEmpty(isolate);
  options.Get(options::kWebPreferences, &web_preferences);
  
  v8::Local<v8::Value> value;
  if (options.Get(options::kBackgroundColor, &value))
    web_preferences.Set(options::kBackgroundColor, value);
  v8::Local<v8::Value> transparent;
  if (options.Get("transparent", &transparent))
    web_preferences.Set("transparent", transparent);
  
  auto web_contents = WebContents::Create(isolate, web_preferences);
  web_contents_.Reset(isolate, web_contents.ToV8());
  api_web_contents_ = web_contents.get();
  
  mate::Dictionary(isolate, web_contents->GetWrapper()).Set(
      "browserWindowOptions", options);
  
  mate::Handle<Window> parent;
  if (options.Get("parent", &parent))