Google’s Project Mainline is an effort to update core system components through the Google Play Services architecture and the Google Play Store. There are three different file types that may be used to distribute a Mainline module: APK, APEX, and APK-in-APEX. A “Google Play System Update” (GPSU) message appears when an update is available for a Mainline module. Effectively, Google has chosen to perform the job of updating crucial components itself, rather than waiting for an OEM to do it. The first official release of the Extension SDK has been made available to the public and is being distributed to devices in the form of a system module.
Although the new Photo Picker API was introduced with Android 13, its accessibility to devices that run 11 and later is the primary benefit of the extension SDK for programmers. Additionally, Google has announced that AdServices APIs will be available to developers in preparation for the beta release of the Android Privacy Sandbox later this year. It demonstrates how the Extension SDK may be used to retroactively add functionality to previous versions of Android without having a complete system reinstall.
Like other device properties, such as build version, the Extension SDK version installed on a user’s device may be queried by developers during runtime. Version 4 of the Extension SDK includes the AdServices API, however Photo Picker has been available from version 2.
When using Android Studio Flamingo or later, developers may have the Extension SDK produce the appropriate version checks for newly released APIs automatically. It’s not required, although it might help programmers incorporate future enhancements. The SDK Extensions documentation includes information on the Privacy Sandbox Beta and the image selector.