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 526cc3d65a6c31637b8bb14fc2c2526ce77db41c..188e674cdfb468da4ca97d77e112b3587d3ae223 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_);