Fix cc scrollbar layer issues with initialization, and use element ids throughout.

cc/layers/scrollbar_layer_impl_base.cc

 // Copyright 2013 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/layers/scrollbar_layer_impl_base.h"
 
 #include <algorithm>
 #include "cc/trees/effect_node.h"
 #include "cc/trees/layer_tree_impl.h"
 #include "ui/gfx/geometry/rect_conversions.h"
@@ skipping 206 matching lines @@
       thumb_thickness_scale_factor_);
 }
 
 void ScrollbarLayerImplBase::SetOverlayScrollbarLayerOpacityAnimated(
     float opacity) {
   DCHECK(is_overlay_scrollbar());
   if (!layer_tree_impl())
     return;
 
   PropertyTrees* property_trees = layer_tree_impl()->property_trees();
-  int effect_node_index =
-      property_trees->effect_tree.FindNodeIndexFromOwningLayerId(id());
-  // 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 (effect_node_index == EffectTree::kInvalidNodeId ||
-      effect_node_index != effect_tree_index())
-    return;
 
   EffectNode* node = property_trees->effect_tree.Node(effect_tree_index());
   if (node->opacity == opacity)
     return;
 
-  layer_tree_impl()->AddToOpacityAnimationsMap(id(), opacity);
-
   node->opacity = opacity;
   node->effect_changed = true;
   property_trees->changed = true;
   property_trees->effect_tree.set_needs_update(true);
   layer_tree_impl()->set_needs_update_draw_properties();
 }
 
 }  // namespace cc