cc : Move screen space scale factor to root transform node

cc/trees/layer_tree_impl.cc

Index: cc/trees/layer_tree_impl.cc
diff --git a/cc/trees/layer_tree_impl.cc b/cc/trees/layer_tree_impl.cc
index 89035df5acb5fefdcaf9ac8ef63e2b78e05c1aca..1c51f07e484dc67fda056500f17e04bbd5fe7ecb 100644
--- a/cc/trees/layer_tree_impl.cc
+++ b/cc/trees/layer_tree_impl.cc
@@ -1032,15 +1032,11 @@ bool LayerTreeImpl::UpdateDrawProperties(
           property_trees()->ComputeTransformToTarget(
               it->render_surface()->TransformTreeIndex(),
               occlusion_surface->EffectTreeIndex(), &draw_transform);
-          // We don't have to apply surface contents scale when target is root.
-          if (occlusion_surface->EffectTreeIndex() !=
-              EffectTree::kContentsRootNodeId) {
-            const EffectNode* occlusion_effect_node =
-                property_trees()->effect_tree.Node(
-                    occlusion_surface->EffectTreeIndex());
-            draw_property_utils::PostConcatSurfaceContentsScale(
-                occlusion_effect_node, &draw_transform);
-          }
+          const EffectNode* occlusion_effect_node =
+              property_trees()->effect_tree.Node(
+                  occlusion_surface->EffectTreeIndex());
+          draw_property_utils::PostConcatSurfaceContentsScale(
+              occlusion_effect_node, &draw_transform);
           const EffectNode* effect_node = property_trees()->effect_tree.Node(
               it->render_surface()->EffectTreeIndex());
           draw_property_utils::ConcatInverseSurfaceContentsScale(