cc: Fix missing render surfaces with output requests

cc/trees/layer_tree_host_common.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_host_common.h"
 
 #include <algorithm>
 
 #include "base/trace_event/trace_event.h"
 #include "cc/base/math_util.h"
@@ skipping 1185 matching lines @@
   void Merge(const PreCalculateMetaInformationRecursiveData& data) {
     layer_or_descendant_has_copy_request |=
         data.layer_or_descendant_has_copy_request;
     layer_or_descendant_has_input_handler |=
         data.layer_or_descendant_has_input_handler;
     num_unclipped_descendants +=
         data.num_unclipped_descendants;
   }
 };
 
+static bool ValidateRenderSurface(LayerImpl* layer) {
+  // This test verifies that there are no cases where a LayerImpl needs
+  // a render surface, but doesn't have one.
+  if (layer->render_surface())
+    return true;
+
+  return layer->filters().IsEmpty() && layer->background_filters().IsEmpty() &&
+         !layer->mask_layer() && !layer->replica_layer() &&
+         !IsRootLayer(layer) && !layer->is_root_for_isolated_group() &&
+         !layer->HasCopyRequest();
+}
+
+static bool ValidateRenderSurface(Layer* layer) {
+  return true;
+}
+
 // Recursively walks the layer tree to compute any information that is needed
 // before doing the main recursion.
 template <typename LayerType>
 static void PreCalculateMetaInformation(
     LayerType* layer,
     PreCalculateMetaInformationRecursiveData* recursive_data) {
+  DCHECK(ValidateRenderSurface(layer));
+
   layer->draw_properties().sorted_for_recursion = false;
   layer->draw_properties().has_child_with_a_scroll_parent = false;
 
   if (!HasInvertibleOrAnimatedTransform(layer)) {
     // Layers with singular transforms should not be drawn, the whole subtree
     // can be skipped.
     return;
   }
 
   if (layer->clip_parent())
@@ skipping 1336 matching lines @@
       inputs->current_render_surface_layer_list_id);
 
   // The dummy layer list should not have been used.
   DCHECK_EQ(0u, dummy_layer_list.size());
   // A root layer render_surface should always exist after
   // CalculateDrawProperties.
   DCHECK(inputs->root_layer->render_surface());
 }
 
 }  // namespace cc