Harrison, then a lawyer at Wilson Sonsini Goodrich & Rosati, joined Google in 2005. After a dozen years working the legal side of deals, he took over the business side when his predecessor, David Lawee, left to oversee a new Google investment arm. Under Harrison, the pace of deals has accelerated with the acquisitions of Waze, the navigation app; Nest, the smart home devices maker; DeepMind Technologies, an artificial intelligence startup; and a string of robotics companies.

In his first interview since he became vice president of corporate development, Harrison spoke with Fortune about how CEO Larry Page thinks about acquisitions.

Fortune: It seems like Larry Page wants to use M&A more aggressively to push Google in new directions.

Harrison: Larry does want to be active in identifying areas where we can make big bets, were we can use moonshot thinking.

Over the past year, a lot of deals are for companies that have ended up over at Google X, the semi-secret lab were Google cooks up its most advanced projects. What kind of mandate has Larry given you?

They are not so much Google X as new product areas within Google. At its highest level the mandate is to find interesting companies that are moving things forward that are solving big problems.

Our acquisitions generally fall into three rough buckets. We look for smaller deals that are focused on talent and technology. We also focus on areas where we identified a core functionality that we are we are trying to implement across a product, and we can fill out that offering as a result of buying companies. There’s a third area, which is still core, where we recognize that we need to be in an area, but we need to get to scale quickly.

Those three have been fairly consistent since 2007. This year, I sort of got to add to that this desire from Larry to really identify some big bets and add new product areas [to Google].

So what are the deals that fall under the new mandate to stretch Google into new areas?

Nest and Andy Rubin efforts are the biggest examples of this. Andy’s efforts in automation are about building a new product area. We have helped him buy seven or eight companies that he has assembled into a pretty comprehensive approach to automation. Those are areas that Google as a whole has been interested in. [They] are somewhat outside the core, but we see a future where those things can work very well with our existing products and services.

A lot of people see Nest as a jumping-off point to building hardware in new areas. Are they right?

At this stage, it’s really about helping [Nest CEO] Tony Fadell achieve his vision as fast as possible. And we believe that if we achieve his vision as fast as possible then it really opens up some opportunities in the future.

Nest was a Google Ventures investment. Is Google Ventures a sort of lead generation machine for Google’s M&A?

We have a very strong ethical wall that prevents us from sharing information back and forth. I have a very close relationship with the partners at Google Ventures and with Bill Maris [who heads the venture group], but it’s the same relationship I have at Kleiner Perkins or at Andreessen Horowitz and all the major VCs.

When you are negotiating a deal like Nest, isn’t there an inherent conflict of interest? Google wants the lowest possible price, and Google Ventures presumably wants the highest possible price.

We have very strong rules in order to protect ourselves, but also to protect the target companies. Where I’m involved, Google Ventures will recuse themselves. In Nest, I negotiated with Kleiner [an early investor in Nest], and I negotiated with Tony [Fadell]. Google Ventures stayed out of providing advice in connection with the acquisition. And we do that across all our acquisitions were we are interested in a Google Ventures portfolio company.

Early on, Google was not known as the best acquirer of companies from the point of view of entrepreneurs. How much had to work at this?

We now have leads on my team that are embedded in the different product areas at Google. They’re very closely in tune with the strategy for each of these product areas. There is a much tighter fit in terms of understanding what deals we look at and what deals are successful.

On the integration backend, we are data-driven and we’re focused. We’ll still make mistakes, but we have the processes in place to make sure we don’t make the same mistake twice.

You mentioned mistakes. Many people see your recent deal to sell the Motorola handset business to Lenovo as unwinding a mistake, even though the initial acquisition of Motorola was in large part to buy its patent portfolio, which Google has kept.

I think the Motorola transaction has been a success for us. Financially, we bought the asset for $12.5 billion. It had $3 billion in cash; we were able to sell the Home division for $2.5 billion; we ended selling the handset division for $3 billion. There were some other tax assets as well. When you work through the math, you realize we spent between $2.5 billion and $3.5 billion for the patent assets. At the time, the nearest comparable transaction was the Nortel patent auction where Microsoft (MSFT) and Apple (AAPL) teamed up to buy that asset for $4.5 billion. And there’s a good argument that the Motorola patent portfolio is a better portfolio.

As Larry noted, if you want to compete in the [handset] space you do need to be all in. We realized that Lenovo as a partner was all in, so that transaction made sense.

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