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.cc
options.Get(options::kResizable, &resizable_);
  options.Get(options::kMinimizable, &minimizable_);
  options.Get(options::kMaximizable, &maximizable_);
  
  options.Get("thickFrame", &thick_frame_);
  if (transparent())
    thick_frame_ = false;
#endif
  if (enable_larger_than_screen())
    
    
    
    
    SetContentSizeConstraints(extensions::SizeConstraints(
        gfx::Size(), gfx::Size(INT_MAX / 10, INT_MAX / 10)));
  int width = 800, height = 600;
  options.Get(options::kWidth, &width);
  options.Get(options::kHeight, &height);
  gfx::Rect bounds(0, 0, width, height);
  widget_size_ = bounds.size();
  window_->AddObserver(this);
  views::Widget::InitParams params;
  params.ownership = views::Widget::InitParams::WIDGET_OWNS_NATIVE_WIDGET;
  params.bounds = bounds;
  params.delegate = this;
  params.type = views::Widget::InitParams::TYPE_WINDOW;
  params.remove_standard_frame = !has_frame();
  if (transparent())