As far as I know, you do not need to host the actual image of the chart. On the contrary, you provide the chart parameters as a URL, it get created and hosted by Google, and you get shown the result.
So all you have to do is add an image and set it's source to create the desired chart.
Case in point:
PS based on recommendation in comments: Shortening the URL is a great idea. i.e., the last chart can be embedded as
tinyurl.com/y7fqgyd - tried it and it works