Remove scroll layer ids from scrollbar layers

cc/trees/layer_tree_impl.cc

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/trees/layer_tree_impl.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 1713 matching lines @@
   if (!scroll_element_id)
     return;
 
   element_id_to_scrollbar_layer_ids_.insert(
       std::pair<ElementId, int>(scroll_element_id, scrollbar_layer->id()));
   if (IsActiveTree() && scrollbar_layer->is_overlay_scrollbar()) {
     layer_tree_host_impl_->RegisterScrollbarAnimationController(
         scroll_element_id);
   }
 
-  DidUpdateScrollState(scrollbar_layer->ScrollLayerId());
+  // TODO(pdr): Refactor DidUpdateScrollState to use ElementIds instead of
+  // layer ids and remove this use of LayerIdByElementId.
+  DidUpdateScrollState(LayerIdByElementId(scroll_element_id));
 }
 
 void LayerTreeImpl::UnregisterScrollbar(
     ScrollbarLayerImplBase* scrollbar_layer) {
   ElementId scroll_element_id = scrollbar_layer->scroll_element_id();
   if (!scroll_element_id)
     return;
 
   auto scrollbar_range =
       element_id_to_scrollbar_layer_ids_.equal_range(scroll_element_id);
@@ skipping 439 matching lines @@
 
 void LayerTreeImpl::ResetAllChangeTracking() {
   layers_that_should_push_properties_.clear();
   // Iterate over all layers, including masks.
   for (auto& layer : *layers_)
     layer->ResetChangeTracking();
   property_trees_.ResetAllChangeTracking();
 }
 
 }  // namespace cc