As we are rolling out the user profile feature, we'd like to expand the [Usage API](https://www.elastic.co/guide/en/elasticsearch/reference/current/usage-api.html) to report usage stats of user profiles such as (1) number of enabled user profiles and (2) number of user profiles that are [activated](https://www.elastic.co/guide/en/elasticsearch/reference/current/security-api-activate-user-profile.html) over the past X days. 

Response of the Usage API already contains a `security` field that groups relevant stats from security related features. We expect the new stats for user profiles should be added under it as well, for example:
```
{
  "security: {
    "user_profile": {
      "activated": 78,
      "recently_activated": 42  <1>
    }
  }
}
```
<1> The use of `recently_` is chosen to avoid the field to be tied to a specific time period so it is easier to evolve the definition in future.

x-pack/plugin/security/src/main/java/org/elasticsearch/xpack/security/profile/ProfileService.java
ThreadPool.Names.GENERIC
                        );
                } else {
                    
                    
                    listener.onFailure(
                        new ElasticsearchException("failed to retrieving profile [{}] after all retries", profileDocument.uid())
                    );
                }
                return;
            }
            
            if (subject.canAccessResourcesOf(versionedDocument.doc.user().toSubject())) {
                
                
                logger.debug(
                    "found existing profile document [{}] accessible to the current subject with username [{}] and realm name [{}]",
                    versionedDocument.doc.uid(),
                    subject.getUser().principal(),
                    subject.getRealm().getName()
                );
                updateProfileForActivate(subject, versionedDocument, listener);
            } else {
                
                
                
                
                
                maybeIncrementDifferentiatorAndCreateNewProfile(subject, profileDocument, listener);
            }