Replace layer id with Element id for tracking scrollbar animation controllers

cc/trees/layer_tree_host_unittest_damage.cc

Index: cc/trees/layer_tree_host_unittest_damage.cc
diff --git a/cc/trees/layer_tree_host_unittest_damage.cc b/cc/trees/layer_tree_host_unittest_damage.cc
index d2f0b861add16edc1d7f3b9ee042e275c70ecf07..d09774497cfbe67659f391a78ae352a36f1887ce 100644
--- a/cc/trees/layer_tree_host_unittest_damage.cc
+++ b/cc/trees/layer_tree_host_unittest_damage.cc
@@ -350,8 +350,8 @@ class LayerTreeHostScrollbarDamageTest : public LayerTreeHostDamageTest {
     scroll_clip_layer->AddChild(content_layer_);
     root_layer->AddChild(scroll_clip_layer);
 
-    scoped_refptr<Layer> scrollbar_layer =
-        FakePaintedScrollbarLayer::Create(false, true, content_layer_->id());
+    scoped_refptr<Layer> scrollbar_layer = FakePaintedScrollbarLayer::Create(
+        false, true, content_layer_->id(), content_layer_->element_id());
     scrollbar_layer->SetPosition(gfx::PointF(300.f, 300.f));
     scrollbar_layer->SetBounds(gfx::Size(10, 100));
     root_layer->AddChild(scrollbar_layer);