Chrome makes Google lots of money directly? I'm not so sure about that.
A post on the Huffington has advertisements alongside it making the company money. That alone makes it much more a grey area than contributing to an open source project.
It seems it is a trade off good writers are choosing to make and if there is more value in their writing a competitor will come along and steal the best writers.
Chrome makes Google money in the same way that articles make the Huffington post money.
The Huffington Post makes money on ads. Every user who uses Google Chrome is a user that isn't using another browser. This means Google makes more money on search ads because they aren't giving a cut to Mozilla, Apple, etc.
I don't find this exploitive, and I think this is very similar.