Replace layer id with Element id for tracking scrollbar animation controllers

cc/trees/layer_tree_host_unittest_context.cc

Index: cc/trees/layer_tree_host_unittest_context.cc
diff --git a/cc/trees/layer_tree_host_unittest_context.cc b/cc/trees/layer_tree_host_unittest_context.cc
index f7bed32bf9e4626dbc64773bae70dd6060aff02d..a1c37a7ba1d0de2f6ff1368a7f8e32115e9ef229 100644
--- a/cc/trees/layer_tree_host_unittest_context.cc
+++ b/cc/trees/layer_tree_host_unittest_context.cc
@@ -971,7 +971,8 @@ class LayerTreeHostContextTestDontUseLostResources
 
     scoped_refptr<PaintedScrollbarLayer> scrollbar =
         PaintedScrollbarLayer::Create(
-            std::unique_ptr<Scrollbar>(new FakeScrollbar), layer->id());
+            std::unique_ptr<Scrollbar>(new FakeScrollbar), layer->id(),
+            layer->element_id());
     scrollbar->SetBounds(gfx::Size(10, 10));
     scrollbar->SetIsDrawable(true);
     root->AddChild(scrollbar);
@@ -1086,8 +1087,8 @@ class ScrollbarLayerLostContext : public LayerTreeHostContextTest {
 
   void BeginTest() override {
     scoped_refptr<Layer> scroll_layer = Layer::Create();
-    scrollbar_layer_ =
-        FakePaintedScrollbarLayer::Create(false, true, scroll_layer->id());
+    scrollbar_layer_ = FakePaintedScrollbarLayer::Create(
+        false, true, scroll_layer->id(), scroll_layer->element_id());
     scrollbar_layer_->SetBounds(gfx::Size(10, 100));
     layer_tree_host()->root_layer()->AddChild(scrollbar_layer_);
     layer_tree_host()->root_layer()->AddChild(scroll_layer);