Google announces its first datacenter for LatAm in Chile
thenextweb.com
thenextweb.com
Another point is, the data center will serve all LatAm not just Chile, so what really matters is where in the region you can get the fastests and more reliable bandwidth links to the US at the lowest price..
You seem to imply that Brazil may be lacking political stability, infrastructure and/or trained professionals, but I don´t know to what extent this would be true. You have to consider that, aside from the economy, Brazil has up to 34% of all latin american population with the vast majority of it living on the eastern coast line. Placing a data center on the west coast does not add up.
There might be some other underlying reason why Google decided to settle in Chile. Maybe the cooler climate can reduce their operational costs.