cc: Mark layers with invalid property tree indices as non-drawable.

cc/trees/draw_property_utils.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/trees/draw_property_utils.h"
 
 #include <stddef.h>
 
 #include <vector>
 
@@ skipping 833 matching lines @@
   const EffectTree& effect_tree = property_trees->effect_tree;
 
   for (auto* layer_impl : *layer_tree_impl) {
     DCHECK(layer_impl);
     DCHECK(layer_impl->layer_tree_impl());
     // TODO(crbug.com/726423) : This is a workaround for crbug.com/725851 to
     // avoid crashing when layer_impl is nullptr. This workaround should be
     // removed as layer_impl should not be nullptr here.
     if (!layer_impl || !layer_impl->HasValidPropertyTreeIndices())
       continue;
+
     if (!IsRootLayer(layer_impl) &&
         LayerShouldBeSkippedForDrawPropertiesComputation(
             layer_impl, transform_tree, effect_tree))
       continue;
 
     bool layer_is_drawn =
         effect_tree.Node(layer_impl->effect_tree_index())->is_drawn;
 
     if (LayerNeedsUpdate(layer_impl, layer_is_drawn, property_trees))
       visible_layer_list->push_back(layer_impl);
@@ skipping 214 matching lines @@
 void UpdateElasticOverscroll(PropertyTrees* property_trees,
                              const Layer* overscroll_elasticity_layer,
                              const gfx::Vector2dF& elastic_overscroll) {
   UpdateElasticOverscrollInternal(property_trees, overscroll_elasticity_layer,
                                   elastic_overscroll);
 }
 
 }  // namespace draw_property_utils
 
 }  // namespace cc