cc : Simplify layer skipping logic

cc/trees/property_tree.cc

 // Copyright 2014 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 <stddef.h>
 
 #include <set>
 #include <vector>
 
 #include "base/logging.h"
@@ skipping 1226 matching lines @@
   if (parent_node)
     node->data.screen_space_opacity *= parent_node->data.screen_space_opacity;
 }
 
 void EffectTree::UpdateIsDrawn(EffectNode* node, EffectNode* parent_node) {
   // Nodes that have screen space opacity 0 are hidden. So they are not drawn.
   // Exceptions:
   // 1) Nodes that contribute to copy requests, whether hidden or not, must be
   //    drawn.
   // 2) Nodes that have a background filter.
-  // 3) Nodes with animating screen space opacity are drawn if their parent is
-  //    drawn irrespective of their opacity.
+  // 3) Nodes with animating screen space opacity on main thread or pending tree
+  //    are drawn if their parent is drawn irrespective of their opacity.
   if (node->data.has_copy_request)
     node->data.is_drawn = true;
-  else if (node->data.opacity == 0.f && !node->data.has_animated_opacity &&
+  else if (node->data.opacity == 0.f &&
+           (!node->data.has_animated_opacity || property_trees()->is_active) &&
            !node->data.has_background_filters)
     node->data.is_drawn = false;
   else if (parent_node)
     node->data.is_drawn = parent_node->data.is_drawn;
   else
     node->data.is_drawn = true;
 }
 
 void EffectTree::UpdateEffectChanged(EffectNode* node,
                                      EffectNode* parent_node) {
@@ skipping 59 matching lines @@
   }
   set_needs_update(true);
 }
 
 bool EffectTree::ContributesToDrawnSurface(int id) {
   // All drawn nodes contribute to drawn surface.
   // Exception : Nodes that are hidden and are drawn only for the sake of
   // copy requests.
   EffectNode* node = Node(id);
   EffectNode* parent_node = parent(node);
-  bool contributes_to_drawn_surface =
-      node->data.is_drawn &&
-      (node->data.opacity != 0.f || node->data.has_animated_opacity ||
-       node->data.has_background_filters);
-  if (parent_node && !parent_node->data.is_drawn)
-    contributes_to_drawn_surface = false;
-  return contributes_to_drawn_surface;
+  return node->data.is_drawn && (!parent_node || parent_node->data.is_drawn);
 }
 
 void EffectTree::ResetChangeTracking() {
   for (int id = 1; id < static_cast<int>(size()); ++id) {
     EffectNode* node = Node(id);
     node->data.effect_changed = false;
   }
 }
 
 void TransformTree::UpdateNodeAndAncestorsHaveIntegerTranslations(
@@ skipping 606 matching lines @@
       break;
     case ALL_TREES:
       transform_tree.ResetChangeTracking();
       effect_tree.ResetChangeTracking();
   }
   changed = false;
   full_tree_damaged = false;
 }
 
 }  // namespace cc