cc: Fix animated filter render surface check

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 573 matching lines @@
     DCHECK(!is_root);
     return true;
   }
 
   // If the layer uses a CSS filter.
   if (!layer->filters().IsEmpty() || !layer->background_filters().IsEmpty()) {
     DCHECK(!is_root);
     return true;
   }
 
+  // If the layer will use a CSS filter.  In this case, the animation
+  // will start and add a filter to this layer, so it needs a surface.
+  if (layer->FilterIsAnimating()) {
+    DCHECK(!is_root);
+    return true;
+  }
+
   int num_descendants_that_draw_content =
       layer->NumDescendantsThatDrawContent();
 
   // If the layer flattens its subtree, but it is treated as a 3D object by its
   // parent (i.e. parent participates in a 3D rendering context).
   if (LayerIsInExisting3DRenderingContext(layer) &&
       layer->should_flatten_transform() &&
       num_descendants_that_draw_content > 0) {
     TRACE_EVENT_INSTANT0(
         "cc",
@@ skipping 587 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) {
+static void 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;
 
-  return layer->filters().IsEmpty() && layer->background_filters().IsEmpty() &&
-         !layer->mask_layer() && !layer->replica_layer() &&
-         !IsRootLayer(layer) && !layer->is_root_for_isolated_group() &&
-         !layer->HasCopyRequest();
+  DCHECK(layer->filters().IsEmpty()) << "layer: " << layer->id();
+  DCHECK(layer->background_filters().IsEmpty()) << "layer: " << layer->id();
+  DCHECK(!layer->mask_layer()) << "layer: " << layer->id();
+  DCHECK(!layer->replica_layer()) << "layer: " << layer->id();
+  DCHECK(!IsRootLayer(layer)) << "layer: " << layer->id();
+  DCHECK(!layer->is_root_for_isolated_group()) << "layer: " << layer->id();
+  DCHECK(!layer->HasCopyRequest()) << "layer: " << layer->id();

[Ian Vollick, 2015/02/25 20:26:38]

Ah nice - thanks! This'll give much better errors.

 }
 
-static bool ValidateRenderSurface(Layer* layer) {
-  return true;
+static void ValidateRenderSurface(Layer* layer) {
 }
 
 // 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));
+  ValidateRenderSurface(layer);
 
   layer->draw_properties().sorted_for_recursion = false;
   layer->draw_properties().has_child_with_a_scroll_parent = false;
   layer->draw_properties().visited = false;
 
   if (!HasInvertibleOrAnimatedTransform(layer)) {
     // Layers with singular transforms should not be drawn, the whole subtree
     // can be skipped.
     return;
   }
@@ skipping 1341 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