App Ops may be the most interesting dumpsys service. The term App Ops is generally used to refer to permissions accessible by an application. In older versions of Android, it was rumored that Google would include the ability for users to revoke specific permissions from an application. This has never come to fruition, but this service at least remains, and shows the last time an application used each permission that it can access. The following is another example from Google Chrome:

In the preceding output, we can see that approximately 1 hour and 7 minutes before appops was dumped with dumpsys, Chrome used the TAKE_AUDIO_FOCUS permission, and later used AUDIO_MEDIA_VOLUME. This indicates that Chrome was used to listen to something, and when it happened.

A somewhat more interesting example is the phone application:

44 minutes ago, the user used the phone application and required the READ_CONTACTS permission, then immediately also used the WRITE_CALL_LOG permission. We can surmise that the user made a phone call 44 minutes ago; even if they had deleted the call from the records afterwards.