cc: DCHECK that the OutputSurface was released in ~LayerTreeHostImpl().

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 82 matching lines @@
   DCHECK(LayerListIsEmpty());
   DCHECK(layers_->empty());
 }
 
 void LayerTreeImpl::Shutdown() {
   DetachLayers();
   DCHECK(LayerListIsEmpty());
 }
 
 void LayerTreeImpl::ReleaseResources() {
+#if DCHECK_IS_ON()
+  // These DCHECKs catch tests that add layers to the tree but fail to build the
+  // layer list afterward.
+  LayerListIterator<LayerImpl> it(root_layer_);
+  size_t i = 0;
+  for (; it != LayerListIterator<LayerImpl>(nullptr); ++it, ++i) {
+    DCHECK_LT(i, layer_list_.size());
+    DCHECK_EQ(layer_list_[i], *it);
+  }
+#endif
+
   if (!LayerListIsEmpty()) {
     LayerTreeHostCommon::CallFunctionForEveryLayer(
         this, [](LayerImpl* layer) { layer->ReleaseResources(); });
   }
 }
 
 void LayerTreeImpl::RecreateResources() {
   if (!LayerListIsEmpty()) {
     LayerTreeHostCommon::CallFunctionForEveryLayer(
         this, [](LayerImpl* layer) { layer->RecreateResources(); });
@@ skipping 1977 matching lines @@
 
 void LayerTreeImpl::ResetAllChangeTracking() {
   layers_that_should_push_properties_.clear();
   // Iterate over all layers, including masks and replicas.
   for (auto& layer : *layers_)
     layer->ResetChangeTracking();
   property_trees_.ResetAllChangeTracking();
 }
 
 }  // namespace cc