Revert of Remove UpdateScrollTree

cc/trees/draw_property_utils.cc

Index: cc/trees/draw_property_utils.cc
diff --git a/cc/trees/draw_property_utils.cc b/cc/trees/draw_property_utils.cc
index 1438d743f2090793ccbe322b573b39ba13353f86..27eb425da9995d22ce9b3ac02f1f37b16c99cbdf 100644
--- a/cc/trees/draw_property_utils.cc
+++ b/cc/trees/draw_property_utils.cc
@@ -743,6 +743,23 @@
   }
 }
 
+static void UpdateScrollTree(ScrollTree* scroll_tree,
+                             const LayerTreeHost* layer_tree_host) {
+  if (!scroll_tree->needs_update())
+    return;
+
+  for (int i = ScrollTree::kRootNodeId;
+       i < static_cast<int>(scroll_tree->size()); ++i) {
+    ScrollNode* scroll_node = scroll_tree->Node(i);
+    if (Layer* scroll_layer =
+            layer_tree_host->LayerById(scroll_node->owning_layer_id)) {
+      if (Layer* scroll_clip_layer = scroll_layer->scroll_clip_layer()) {
+        scroll_node->scroll_clip_layer_bounds = scroll_clip_layer->bounds();
+      }
+    }
+  }
+}
+
 static void ComputeClips(PropertyTrees* property_trees) {
   DCHECK(!property_trees->transform_tree.needs_update());
   ClipTree* clip_tree = &property_trees->clip_tree;
@@ -872,6 +889,7 @@
     property_trees->clip_tree.set_needs_update(true);
     property_trees->effect_tree.set_needs_update(true);
   }
+  UpdateScrollTree(&property_trees->scroll_tree, layer_tree_host);
   ComputeTransforms(&property_trees->transform_tree);
   ComputeEffects(&property_trees->effect_tree);
   // Computation of clips uses ToScreen which is updated while computing