Just for record, I found this issue on google visualization repo: https://github.com/google/google-visualization-issues/issues/2292 They answer:
> Thanks for reporting this. We observed this happening recently, and are > working on setting up an API key to avoid that warning message. I believe > the sensor message will be avoided with our new way of using the maps API. > You can try it now by changing 'current' to 'upcoming' in your > google.charts.load() call. > -- You received this message because you are subscribed to the Google Groups "Google Visualization API" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/google-visualization-api. To view this discussion on the web visit https://groups.google.com/d/msgid/google-visualization-api/36ac49e9-99e3-4acb-b287-8482758e1f49%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
