Notifications for a few merge-related scenarios

ts/services/storage.ts

@@ -1732,6 +1732,12 @@ async function sync(
 
     // We now know that we've successfully completed a storage service fetch
     await window.storage.put('storageFetchComplete', true);
+
+    if (window.CI) {
+      window.CI.handleEvent('storageServiceComplete', {
+        manifestVersion: version,
+      });
+    }
   } catch (err) {
     log.error(
       'storageService.sync: error processing manifest',