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/Security.java
this.securityExtensions.addAll(extensions);
    }
    private static void runStartupChecks(Settings settings) {
        validateRealmSettings(settings);
        if (XPackSettings.FIPS_MODE_ENABLED.get(settings)) {
            validateForFips(settings);
        }
    }
    
    protected Clock getClock() {
        return Clock.systemUTC();
    }
    protected SSLService getSslService() {
        return XPackPlugin.getSharedSslService();
    }
    protected XPackLicenseState getLicenseState() {
        return XPackPlugin.getSharedLicenseState();
    }
    @Override
    public Collection<Object> createComponents(
        Client client,
        ClusterService clusterService,
        ThreadPool threadPool,
        ResourceWatcherService resourceWatcherService,
        ScriptService scriptService,
        NamedXContentRegistry xContentRegistry,
        Environment environment,
        NodeEnvironment nodeEnvironment,
        NamedWriteableRegistry namedWriteableRegistry,
        IndexNameExpressionResolver expressionResolver,