Clear experimenter id on telemetry disabled

src/glean/mzglean.cpp

@@ -141,16 +141,26 @@ void MZGlean::setUploadEnabled(bool isTelemetryEnabled) {
 
   broadcastUploadEnabledChange(isTelemetryEnabled);
 
-#if defined(MZ_ANDROID) || defined(MZ_IOS)
   if (isTelemetryEnabled) {
+#if defined(MZ_ANDROID) || defined(MZ_IOS)
     // need to reset installation ID, as it would have been cleared
     QString uuid = mozilla::glean::session::installation_id.generateAndSet();
     SettingsHolder::instance()->setInstallationId(uuid);
+#endif
   } else {
-    // clear out the former installation ID immediately
+    // Note: Identifiers should be rotated when telemetry is disabled.
+    //
+    // Whenever telemetry is disabled, that generates a data deletion request
+    // on the backend. If telemtry is re-enabled, all new identifiers are
+    // generated by Glean, so we also rotate our identifiers to comply.
+
+    // Clear out the experimentation ID
+    SettingsHolder::instance()->removeUnauthedExperimenterId();
+#if defined(MZ_ANDROID) || defined(MZ_IOS)
+    // Clear out the former installation ID
     SettingsHolder::instance()->removeInstallationId();
-  }
 #endif
+  }
 }
 
 // static