DCHECK that property tree access is safe in LayerTreeImpl::DidUpdateScrollState

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 189 matching lines @@
   }
 
   if (IsActiveTree() && layer_tree_host_impl_->pending_tree())
     layer_tree_host_impl_->pending_tree()->DidUpdateScrollOffset(layer_id);
 }
 
 void LayerTreeImpl::DidUpdateScrollState(int layer_id) {
   if (!IsActiveTree())
     return;
 
+  DCHECK(lifecycle().AllowsPropertyTreeAccess());
+
   // The scroll_clip_layer Layer properties should be up-to-date.
   // TODO(pdr): This DCHECK fails on existing tests but should be enabled.
   // DCHECK(lifecycle().AllowsLayerPropertyAccess());
 
   if (layer_id == Layer::INVALID_ID)
     return;
 
   int scroll_layer_id, clip_layer_id;
   if (IsViewportLayerId(layer_id)) {
     if (!InnerViewportContainerLayer())
@@ skipping 1881 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