As general background, OWNERS files expedite code reviews by helping code authors quickly find relevant reviewers, and they also ensure that stakeholders are involved in code changes in their areas.
The structure of frameworks/base/ is unique among Android repositories, and it's evolved into a complex interleaved structure over the years. Because of this structure, the best place to authoritatively define OWNERS can vary wildly, but here are some common patterns:
core/java/ contains source that is included in the base classpath, and as such it's where most APIs are defined:core/java/android/app/core/java/android/content/services/core/ contains most system services, and these directories typically have more granularity than core/java/, since they can be refactored without API changes:services/core/java/com/android/server/net/services/core/java/com/android/server/wm/services/ contains several system services that have been isolated from the main services/core/ project:services/appwidget/services/midi/apex/ contains Mainline modules:apex/jobscheduler/apex/permission/media/wifi/Area maintainers are strongly encouraged to list people in a single authoritative OWNERS file in exactly one location. Then, other paths should reference that single authoritative OWNERS file using an include directive. This approach ensures that updates are applied consistently across the tree, reducing maintenance burden.