Fingernail
Popsicle Stick
Plastic Razor Blade
You need something that will scrape or pry the melted rubber/plastic mix off the chrome coating that at the same time won't scratch the chrome coating.
Usually just takes some grunt work with something like I listed above. I've tried using things like Aircraft Quality Paint Stripper and Easy-Off Oven Cleaner to chemically attack, soften and loosen the bond the melted goo has on the chrome, things like this won't hurt chrome.