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/test/java/org/elasticsearch/xpack/security/SecurityInfoTransportActionTests.java
}
    private void configureRoleMappingStoreUsage(boolean roleMappingStoreEnabled) {
        doAnswer(invocationOnMock -> {
            @SuppressWarnings("unchecked")
            ActionListener<Map<String, Object>> listener = (ActionListener<Map<String, Object>>) invocationOnMock.getArguments()[0];
            if (roleMappingStoreEnabled) {
                final Map<String, Object> map = new HashMap<>();
                map.put("size", 12L);
                map.put("enabled", 10L);
                listener.onResponse(map);
            } else {
                listener.onResponse(Collections.emptyMap());
            }
            return Void.TYPE;
        }).when(roleMappingStore).usageStats(anyActionListener());
    }
    private SecurityUsageTransportAction newUsageAction(Settings settings) {
        return new SecurityUsageTransportAction(
            mock(TransportService.class),
            null,
            null,
            mock(ActionFilters.class),
            null,
            settings,
            licenseState,
            securityServices
        );
    }
}