Google doubled down on its bet on artificial intelligence with new features and availability for its virtual assistant and smart speaker at its annual software-developers conference, part of a scramble with other tech giants to dominate the next wave of consumer technology.

The new uses unveiled Wednesday touch on such popular Google functions as photos, email and mobile payments. They build on two products—Google Assistant and Google Home—announced at last year’s conference. But there was also a nod to a new computing platform:...