Sometime last week Google pushed out a new update for its Gmail Android app that brought new visual changes including conversation view with card-based design, improved sync and outbox and a couple of other updates, as well as support for ads, found burried deep in the APK, according to Android Police.
During the teardown of the APK, Android Police discovered that there are multiple references to ads in the code of the app meaning that it is quite possible that we will soon see some of them in the Gmail Android app as well. It is still not clear how will the app actually show those ads and where will they be as, hopefully, will not ruin the Gmail app and become overly intrusive.
Google puts a lot of faith in ads and Gmail is quite popular making it an obvious choice for Google. According to the teardown, Google has a total of eight different classes including toasts, teaser, sender header, ad header, ad border, and the ad view.
In any case we will know for sure once Google enables them officially.