Android alone accounted for $31b revenue in 2016, according to Oracle, of which $22b was purportedly profit just for 2016. Excluding Android's contribution to their advertising ecosystem, which is another chunk of that $136 billion you mention. That's far more than 10% of their gross profit, but even if it was less why would that absolve Google of responsibility? The % doesn't create the customer the transactions do.
It's probably wrong, just something internal Oracle leaked on a topic without much transparency. But even if all Google ever made was the $25 one-time fee all Play Store developers have paid they meet the criteria to be customers.
It's got to be about 2 decades since only advertisers gave Google money in exchange for goods and services, since then there are dozens of ways to be their customer.
https://www.bloomberg.com/news/articles/2016-01-21/google-s-...