syncbase/vsync: Integrate SyncGroup syncing, and add e2e tests.

MultiPart: 2/2
Change-Id: Ie3e669bb0357fe42b8853e29dd4f08f0eac92a15
diff --git a/services/syncbase/vsync/watcher.go b/services/syncbase/vsync/watcher.go
index 9c16294..5b8b469 100644
--- a/services/syncbase/vsync/watcher.go
+++ b/services/syncbase/vsync/watcher.go
@@ -120,7 +120,7 @@
 	}
 
 	// Initialize Database sync state if needed.
-	s.initSyncStateInMem(ctx, appName, dbName, interfaces.NoGroupId)
+	s.initSyncStateInMem(ctx, appName, dbName, "")
 
 	// Get a batch of watch log entries, if any, after this resume marker.
 	logs, nextResmark, err := watchable.ReadBatchFromLog(st, resMark)