https://www.glassdoor.com/Salary/Google-Salaries-E9079.htm
It seems similar to the way it was at Facebook in that when you start, you'll be assigned a level based on your previous experience and it'll be corrected soon afterwards if it turns out to have been wrong. They mostly corrected up, though - it was very rare for someone to be assigned a high level and then downgraded afterwards.
Obviously the Glassdoor link shows that there is a pretty big range in the salary bands - I think some of this is down to people reporting total target compensation (including RSUs, bonuses etc) versus base salary but there was a fairly large range at FB too. It wasn't uncommon to stay at the same level but have your base salary go up by $20-25k.