Through the API, an app can see all the other apps the user is running and take an action when a specific app launches.
Google has removed the popular "UC Browser" from the Google Play Store.
Google offers Android Accessibility Services that are used by app developers to create apps for users with disabilities. For instance the "Building Accessibility Services" page suggests developers make apps for users "who may temporarily be unable to fully interact with a device".
The policy enforcement could affect apps like LastPass, Tasker, Cereberus and Universal Copy that use accessibility code for key features not intended for handicapped users. "This is really bad news", Universal Copy's developer said on the Reddit Android Reddit.
News broke over the weekend that Google was instructing Android developers that don't use Accessibility Services for its intended objective to strip away that functionality from apps. "I plan to replace app detection with usage stats API", they wrote on a Google forum. Accessibility services code can allow applications to access data in other apps, creating juicy security holes that hackers could exploit to steal private data.
As first reported by XDA Developers, a number of app developers have received an e-mail from Google in regard to their accessibility app.
Google's accessibility restrictions appear to be part of a larger push to improve the security of apps in the Play Store. But not all of them are very useful. We've reached out to Google for more information.