Replace layer id with Element id for tracking scrollbar animation controllers

cc/trees/layer_tree_host_unittest.cc

Index: cc/trees/layer_tree_host_unittest.cc
diff --git a/cc/trees/layer_tree_host_unittest.cc b/cc/trees/layer_tree_host_unittest.cc
index 2e7457a49aac6600be861bf479eb244c545a3d17..df1b9f3650ebaa303d1f657ed4fffd0c9a60cbe5 100644
--- a/cc/trees/layer_tree_host_unittest.cc
+++ b/cc/trees/layer_tree_host_unittest.cc
@@ -1750,7 +1750,8 @@ class LayerTreeHostTestNoExtraCommitFromScrollbarInvalidate
     bool paint_scrollbar = true;
     bool has_thumb = false;
     scrollbar_ = FakePaintedScrollbarLayer::Create(paint_scrollbar, has_thumb,
-                                                   root_layer_->id());
+                                                   root_layer_->id(),
+                                                   root_layer_->element_id());
     scrollbar_->SetPosition(gfx::PointF(0.f, 10.f));
     scrollbar_->SetBounds(gfx::Size(10, 10));
 
@@ -3737,7 +3738,7 @@ class LayerTreeHostTestPropertyChangesDuringUpdateArePushed
     bool paint_scrollbar = true;
     bool has_thumb = false;
     scrollbar_layer_ = FakePaintedScrollbarLayer::Create(
-        paint_scrollbar, has_thumb, root_->id());
+        paint_scrollbar, has_thumb, root_->id(), root_->element_id());
 
     root_->AddChild(scrollbar_layer_);