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
NativeWindow* native_window) {
  auto existing = TrackableObject::FromWrappedClass(isolate, native_window);
  if (existing)
    return existing->GetWrapper();
  else
    return v8::Null(isolate);
}
}  
}  
namespace {
using atom::api::Window;
void Initialize(v8::Local<v8::Object> exports, v8::Local<v8::Value> unused,
                v8::Local<v8::Context> context, void* priv) {
  v8::Isolate* isolate = context->GetIsolate();
  Window::SetConstructor(isolate, base::Bind(&Window::New));
  mate::Dictionary browser_window(
      isolate, Window::GetConstructor(isolate)->GetFunction());
  browser_window.SetMethod("fromId",
                           &mate::TrackableObject<Window>::FromWeakMapID);
  browser_window.SetMethod("getAllWindows",
                           &mate::TrackableObject<Window>::GetAll);
  mate::Dictionary dict(isolate, exports);
  dict.Set("BrowserWindow", browser_window);
}
}  
NODE_MODULE_CONTEXT_AWARE_BUILTIN(atom_browser_window, Initialize)