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.cc
}
void NativeWindow::SetMenu(AtomMenuModel* menu) {
}
void NativeWindow::SetParentWindow(NativeWindow* parent) {
  parent_ = parent;
}
void NativeWindow::FocusOnWebView() {
  web_contents()->GetRenderViewHost()->GetWidget()->Focus();
}
void NativeWindow::BlurWebView() {
  web_contents()->GetRenderViewHost()->GetWidget()->Blur();
}
bool NativeWindow::IsWebViewFocused() {
  auto host_view = web_contents()->GetRenderViewHost()->GetWidget()->GetView();
  return host_view && host_view->HasFocus();
}
void NativeWindow::SetAutoHideMenuBar(bool auto_hide) {
}
bool NativeWindow::IsMenuBarAutoHide() {
  return false;
}
void NativeWindow::SetMenuBarVisibility(bool visible) {
}
bool NativeWindow::IsMenuBarVisible() {
  return true;
}
double NativeWindow::GetAspectRatio() {
  return aspect_ratio_;
}
gfx::Size NativeWindow::GetAspectRatioExtraSize() {