Antitrust requires monopoly, which google does not have. There are many competitive and successful ad networks and search engines, and there is no lock in to the search product.
Without robber-barons, we would have a dearth of philanthropists.
Yes, some of the robber-barons were and are philanthropists.
But robbing to give it away is not much more moral than robbing to spend it yourself or give it to your heirs. Both are still theft.
For examples of modern non-robber philanthropists, see H & P, Buffet, et al.