Feature Request: Don't fire callback until load callback from google maps fires

[tstirrat15]

In our project, we've seen a bunch of "google maps is undefined errors" on mobile devices that seem to have slow connections, and my current hypothesis is the following:

1. Google maps script is injected
2. Bootstrap code is downloaded (i.e. not the library code itself)
3. script onLoad event fires before library code has finished loading
4. Google Maps is treated as loaded, but window.google.maps is still null/undefined.

One fix for the above behavior would be to take advantage of the callback parameter on the google maps JS request.

Is this consistent with your experience? Are there challenges to implementing this? Otherwise I'd be happy to submit a PR.

[cedricdelpoux]

I would be happy to see you PR about this. Thank you very much for your help