ABC’s new drama, “The Days,” has the potential to revolutionize the television industry, but not because of anything that happens to the characters. Instead, ABC is using the miniseries to test out the next generation of product-placement techniques, and is taking a page from the golden age of the medium, when companies sponsored entire programs rather than simpy buying 30-second spots. To advertisers, it’s a way to get value for their ad-buying dollar at a time when most viewers click away from ad blocks. To the network, they hope it’s a way to keep the money rolling in without angering viewers with blatant commercialism.