I'd say iMessage over WhatsApp is the example of how to do it now. If Google copied iMessage feature-wise, syncing it between Chrome, Android and iOS, seamlessl

I'd say iMessage over WhatsApp is the example of how to do it now. If Google copied iMessage feature-wise, syncing it between Chrome, Android and iOS, seamlessly integrating SMS and not, I think they'd have a winner. WhatsApp is simpler but iMessage brings really useful features, and they strongly match Google's key competencies too.