cc: LayerTreeHostImpl uses element id to tick animations

cc/input/scrollbar_animation_controller.cc

 // Copyright 2014 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/input/scrollbar_animation_controller.h"
 
 #include <algorithm>
 
 #include "base/time/time.h"
 #include "cc/trees/layer_tree_impl.h"
@@ skipping 347 matching lines @@
 void ScrollbarAnimationController::Show() {
   delayed_scrollbar_show_.Cancel();
   ApplyOpacityToScrollbars(1.0f);
 }
 
 void ScrollbarAnimationController::ApplyOpacityToScrollbars(float opacity) {
   for (ScrollbarLayerImplBase* scrollbar : Scrollbars()) {
     if (!scrollbar->is_overlay_scrollbar())
       continue;
     float effective_opacity = scrollbar->CanScrollOrientation() ? opacity : 0;
-    PropertyTrees* property_trees =
-        scrollbar->layer_tree_impl()->property_trees();
-    // If this method is called during LayerImpl::PushPropertiesTo, we may not
-    // yet have valid owning_layer_id_to_node_index entries in effect tree as
-    // property trees are pushed after layers during activation. We can skip
-    // updating opacity in that case as we are only registering a scrollbar and
-    // because opacity will be overwritten anyway when property trees are
-    // pushed.
-    if (property_trees->effect_tree.FindNodeIndexFromOwningLayerId(
-            scrollbar->id()) != EffectTree::kInvalidNodeId) {
-      property_trees->effect_tree.OnOpacityAnimated(
-          effective_opacity,
-          property_trees->effect_tree.FindNodeIndexFromOwningLayerId(
-              scrollbar->id()),
-          scrollbar->layer_tree_impl());
-    }
+    scrollbar->SetOverlayScrollbarLayerOpacityAnimated(effective_opacity);
   }
 
   bool previouslyVisible = opacity_ > 0.0f;
   bool currentlyVisible = opacity > 0.0f;
 
   if (opacity_ != opacity)
     client_->SetNeedsRedrawForScrollbarAnimation();
 
   opacity_ = opacity;
 
   if (previouslyVisible != currentlyVisible)
     client_->DidChangeScrollbarVisibility();
 }
 
 }  // namespace cc