The U.S. Justice Department is asking publishers, including Condé Nast, News Corp and The New York Times, for information about Google's business practices as part of a broader antitrust probe, Bloomberg Newsreported last week.

While those publishers wouldn't comment on their meetings with investigators, it's likely they have a litany of complaints to share. Google not only controls how most of the world finds publishers' digital content through its search engine, but it also runs much of the infrastructure that brings media buyers and sellers of ad space together.

While publishers sell ad space directly, many also use Google Ad Manager to oversee auctions of their ad inventories. On the buy side, brands might rely on Google Campaign Manager or Google Display & Video 360 to host their digital ads and manage bidding for inserts.

Publishers and advertisers have complained about the lack of transparency in the digital ad market, as Bloomberg News notes. It's not always clear how prices get set and ad placements are made.

Google has made amends to publishers in the past, and claims that it shares 70% of digital ad revenue with media outlets. Two years ago, it ended its "first-click-free" policy, letting subscription-based publishers determine how many articles they wanted to show before putting up a paywall.

Google last week formalized a long-rumored plan to end support for third-party cookies, a technology to track individuals as they visit different websites. As part of an effort to give consumers more privacy protections, it will phase out third-party cookie support in its Chrome browser in the next two years.

It's too early to tell how the plan will affect the digital advertising market -- publishers, media buyers and ad-tech companies have two years to figure out another tracking technology.

The move may help publishers that collect first-party data about their reader, and don’t have to worry about any restrictions. They can keep on delivering those audiences to advertisers.

As for any antitrust actions by government, regulators may determine that Google needs to undo certain acquisitions -- such as its purchases of DoubleClick, YouTube or Android -- to prevent a single tech giant from controlling too many media platforms.