Use element id's for animations

cc/test/layer_test_common.h

Index: cc/test/layer_test_common.h
diff --git a/cc/test/layer_test_common.h b/cc/test/layer_test_common.h
index 71ce50844582450febd0a5d5bd9ad1712bad2f92..1d26edbb58aae16271f14608eda57ddeddc5ac0f 100644
--- a/cc/test/layer_test_common.h
+++ b/cc/test/layer_test_common.h
@@ -157,6 +157,10 @@ class LayerTestCommon {
     scoped_refptr<AnimationTimeline> timeline() { return timeline_; }
     scoped_refptr<AnimationTimeline> timeline_impl() { return timeline_impl_; }
 
+    void SetElementIdsForTesting() {
+      host_impl()->active_tree()->SetElementIdsForTesting();
+    }
+
    private:
     FakeLayerTreeHostClient client_;
     TestTaskGraphRunner task_graph_runner_;