Two years later, the integration of Google's $750 million acquisition of mobile ad network AdMob into the mothership may finally be complete.

Google is set to announce that AdMob's mobile display ads, which appear in more than 300,000 apps on phones, will now be available in the engine that powers much of Google's $37 billion in annual ad revenue: AdWords. That tool is what Jason Spero, head of global mobile sales and strategy at Google, calls the "nuclear power plant at the core" of the company.

The integration makes it more simple to spend money on mobile ads, since now they can be bought and managed in the same place as other ad efforts, like search and display. Connecting those pipes means the majority of Google's advertisers will have access to a medium that 's suffered from smartphone usage far outpacing the ability for advertisers to spend on the device.

More than 1 million Google advertisers, from small businesses using the company's self-serve tool to big advertisers not currently buying through AdMob's separate storefront, will see mobile display options right alongside the products they usually spend on.

"This is about enabling scale for industry," Mr. Spero said. "Anybody that 's buying performance media through AdWords can now very easily add mobile display to campaigns. We have a lot of customers that buy search and desktop display through one interface. Now they're adding mobile display to that ."

Integrating all its products into one-stop tools is a big focus for the company. Just yesterday, Google made a similar shift bringing together many different ad types on its big agency and marketer platform Doubleclick.

The AdMob-AdWords integration also makes it easier for medium- and small-businesses to spend on Google mobile ads. These businesses are expected to spend $4.5 billion on mobile marketing this year in the U.S. alone, according to Borrell Associates.

Increasing the pool of potential advertisers is crucial for all mobile-ad sellers. In mobile, there's a surplus of ad inventory on phones that 's so far exceeded advertiser demand and has pushed prices down.

A newer entrant into mobile advertising, Facebook, made a similar shift this week, when it opened up its ads on its mobile app to all its advertisers big and small, not just those that could afford premium ad packages.