Saying that google is an ad company is a mistake. Just because that's where the revenue, the sustenance comes from as a primary source. But that revenue exists because of google's market domination in search and other services. If google stopped being a search company their ad revenue would dry up overnight. Saying that google is an ad company is like saying that a particular software dev. is not a "software person" but a "burrito person", because they happen to eat burritos a lot.
At the end of the day google's revenue comes about because they provide something of value to their users, and advertisments are a way to monetize that value effectively. No different than broadcast tv or radio. But it's the value which is the foundation of the company, the revenue is merely a consequence of that value. Thinking that the revenue stream is an intrinsic part of the company is a mistake that has doomed many companies before. Think about newspapers, I'm sure many of them thought of themselves as advertising companies to a substantial degree, and when that revenue dried up because the value of the newspaper changed, many of them were left wondering what to do, many of them have already gone out of business, many more still will. Hopefully google won't make the same mistake and alienate its users more than it has already or ignore competition before it's too late.