Revert of cc : Remove subtree skipping in LayerTreeHostCommon

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 <stddef.h>
 
 #include <algorithm>
 
@@ skipping 524 matching lines @@
   DCHECK_GE(layer->effect_tree_index(), 0);
   layer_is_drawn = property_trees->effect_tree.Node(layer->effect_tree_index())
                        ->data.is_drawn;
 
   // The root layer cannot be skipped.
   if (!IsRootLayer(layer) &&
       draw_property_utils::LayerShouldBeSkipped(layer, layer_is_drawn,
                                                 property_trees->transform_tree,
                                                 property_trees->effect_tree)) {
     layer->draw_properties().render_target = nullptr;
+    return;
+  }
+
+  bool render_to_separate_surface =
+      IsRootLayer(layer) ||
+      (can_render_to_separate_surface && layer->render_surface());
+
+  if (render_to_separate_surface) {
+    DCHECK(layer->render_surface()) << IsRootLayer(layer)
+                                    << can_render_to_separate_surface
+                                    << layer->has_render_surface();
+    layer->draw_properties().render_target = layer;
+
+    if (layer->mask_layer())
+      layer->mask_layer()->draw_properties().render_target = layer;
+
+    if (layer->replica_layer() && layer->replica_layer()->mask_layer())
+      layer->replica_layer()->mask_layer()->draw_properties().render_target =
+          layer;
+
   } else {
-    bool render_to_separate_surface =
-        IsRootLayer(layer) ||
-        (can_render_to_separate_surface && layer->render_surface());
-
-    if (render_to_separate_surface) {
-      DCHECK(layer->render_surface()) << IsRootLayer(layer)
-                                      << can_render_to_separate_surface
-                                      << layer->has_render_surface();
-      layer->draw_properties().render_target = layer;
-
-      if (layer->mask_layer())
-        layer->mask_layer()->draw_properties().render_target = layer;
-
-      if (layer->replica_layer() && layer->replica_layer()->mask_layer())
-        layer->replica_layer()->mask_layer()->draw_properties().render_target =
-            layer;
-
-    } else {
-      DCHECK(!IsRootLayer(layer));
-      layer->draw_properties().render_target = layer->parent()->render_target();
-    }
+    DCHECK(!IsRootLayer(layer));
+    layer->draw_properties().render_target = layer->parent()->render_target();
   }
   for (size_t i = 0; i < layer->children().size(); ++i) {
     CalculateRenderTarget(
         LayerTreeHostCommon::get_layer_as_raw_ptr(layer->children(), i),
         property_trees, layer_is_drawn, can_render_to_separate_surface);
   }
 }
 
 void CalculateRenderSurfaceLayerList(
     LayerImpl* layer,
@@ skipping 26 matching lines @@
                        ->data.is_drawn;
 
   // The root layer cannot be skipped.
   if (!IsRootLayer(layer) &&
       draw_property_utils::LayerShouldBeSkipped(layer, layer_is_drawn,
                                                 property_trees->transform_tree,
                                                 property_trees->effect_tree)) {
     if (layer->render_surface())
       layer->ClearRenderSurfaceLayerList();
     layer->draw_properties().render_target = nullptr;
-    for (auto* child_layer : layer->children()) {
-      CalculateRenderSurfaceLayerList(
-          child_layer, property_trees, render_surface_layer_list, descendants,
-          nearest_occlusion_immune_ancestor, layer_is_drawn,
-          can_render_to_separate_surface, current_render_surface_layer_list_id,
-          max_texture_size);
-    }
     return;
   }
 
   bool render_to_separate_surface =
       IsRootLayer(layer) ||
       (can_render_to_separate_surface && layer->render_surface());
 
   if (render_to_separate_surface) {
     DCHECK(layer->render_surface());
     draw_property_utils::ComputeSurfaceDrawProperties(property_trees,
@@ skipping 26 matching lines @@
     }
     layer->render_surface()->SetNearestOcclusionImmuneAncestor(
         nearest_occlusion_immune_ancestor);
     layer->ClearRenderSurfaceLayerList();
 
     render_surface_layer_list->push_back(layer);
 
     descendants = &(layer->render_surface()->layer_list());
   }
 
+  size_t descendants_size = descendants->size();
+
   bool layer_should_be_skipped = !draw_property_utils::LayerNeedsUpdate(
       layer, layer_is_drawn, property_trees->transform_tree);
   if (!layer_should_be_skipped) {
-    DCHECK(layer->draw_properties().render_target);
     MarkLayerWithRenderSurfaceLayerListId(layer,
                                           current_render_surface_layer_list_id);
     descendants->push_back(layer);
   }
 
 
   // Clear the old accumulated content rect of surface.
   if (render_to_separate_surface)
     layer->render_surface()->SetAccumulatedContentRect(gfx::Rect());
 
@@ skipping 58 matching lines @@
       }
       // The RenderSurfaceImpl backing texture cannot exceed the maximum
       // supported texture size.
       surface_content_rect.set_width(
           std::min(surface_content_rect.width(), max_texture_size));
       surface_content_rect.set_height(
           std::min(surface_content_rect.height(), max_texture_size));
       layer->render_surface()->SetContentRect(surface_content_rect);
     }
     const LayerImpl* parent_target = layer->parent()->render_target();
-    if (parent_target && !IsRootLayer(parent_target)) {
+    if (!IsRootLayer(parent_target)) {
       gfx::Rect surface_content_rect =
           parent_target->render_surface()->accumulated_content_rect();
       if (render_to_separate_surface) {
         // If the layer owns a surface, then the content rect is in the wrong
         // space. Instead, we will use the surface's DrawableContentRect which
         // is in target space as required. We also need to clip it with the
         // target's clip if the target is clipped.
         surface_content_rect.Union(gfx::ToEnclosedRect(
             layer->render_surface()->DrawableContentRect()));
         if (parent_target->is_clipped())
           surface_content_rect.Intersect(parent_target->clip_rect());
       } else if (layer->DrawsContent()) {
         surface_content_rect.Union(layer->drawable_content_rect());
       }
       parent_target->render_surface()->SetAccumulatedContentRect(
           surface_content_rect);
     }
   } else {
     // The root layer's surface content rect is always the entire viewport.
     gfx::Rect viewport =
         gfx::ToEnclosingRect(property_trees->clip_tree.ViewportClip());
     layer->render_surface()->SetContentRect(viewport);
   }
 
   if (render_to_separate_surface && !IsRootLayer(layer) &&
       layer->render_surface()->DrawableContentRect().IsEmpty()) {
     RemoveSurfaceForEarlyExit(layer, render_surface_layer_list);
+    return;
+  }
+
+  // If neither this layer nor any of its children were added, early out.
+  if (descendants_size == descendants->size()) {
+    DCHECK(!render_to_separate_surface || IsRootLayer(layer));
+    return;
   }
 }
 
 static void ComputeMaskLayerDrawProperties(const LayerImpl* layer,
                                            LayerImpl* mask_layer) {
   DrawProperties& mask_layer_draw_properties = mask_layer->draw_properties();
   mask_layer_draw_properties.visible_layer_rect = gfx::Rect(layer->bounds());
   mask_layer_draw_properties.target_space_transform =
       layer->draw_properties().target_space_transform;
   mask_layer_draw_properties.screen_space_transform =
@@ skipping 80 matching lines @@
   }
 
   if (should_measure_property_tree_performance) {
     TRACE_EVENT_BEGIN0(TRACE_DISABLED_BY_DEFAULT("cc.debug.cdp-perf"),
                        "LayerTreeHostCommon::CalculateDrawProperties");
   }
 
   DCHECK(inputs->can_render_to_separate_surface ==
          inputs->property_trees->non_root_surfaces_enabled);
   const bool subtree_visible_from_ancestor = true;
+  for (auto* layer : *inputs->root_layer->layer_tree_impl())
+    layer->draw_properties().render_target = nullptr;
   CalculateRenderTarget(inputs->root_layer, inputs->property_trees,
                         subtree_visible_from_ancestor,
                         inputs->can_render_to_separate_surface);
   for (LayerImpl* layer : visible_layer_list) {
     draw_property_utils::ComputeLayerDrawProperties(
         layer, inputs->property_trees, inputs->layers_always_allowed_lcd_text,
         inputs->can_use_lcd_text);
     if (layer->mask_layer())
       ComputeMaskLayerDrawProperties(layer, layer->mask_layer());
     LayerImpl* replica_mask_layer =
@@ skipping 103 matching lines @@
 
 PropertyTrees* GetPropertyTrees(Layer* layer) {
   return layer->layer_tree_host()->property_trees();
 }
 
 PropertyTrees* GetPropertyTrees(LayerImpl* layer) {
   return layer->layer_tree_impl()->property_trees();
 }
 
 }  // namespace cc