Determine a layer's IsAffectedByPageScale property without using Layer Tree

cc/trees/property_tree_builder.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 "cc/trees/property_tree_builder.h"
 
 #include <stddef.h>
 
 #include <map>
 #include <set>
@@ skipping 610 matching lines @@
     data_for_children->axis_align_since_render_target = true;
   }
   return should_create_render_surface;
 }
 
 template <typename LayerType>
 void BuildPropertyTreesInternal(
     LayerType* layer,
     const DataForRecursion<LayerType>& data_from_parent) {
   layer->set_property_tree_sequence_number(data_from_parent.sequence_number);
+  if (layer->mask_layer())
+    layer->mask_layer()->set_property_tree_sequence_number(
+        data_from_parent.sequence_number);
+
   DataForRecursion<LayerType> data_for_children(data_from_parent);
 
   bool created_render_surface =
       AddEffectNodeIfNeeded(data_from_parent, layer, &data_for_children);
 
   if (created_render_surface) {
     data_for_children.render_target = data_for_children.effect_tree_parent;
     layer->set_draw_blend_mode(SkXfermode::kSrcOver_Mode);
   } else {
     layer->set_draw_blend_mode(layer->blend_mode());
   }
 
+  if (layer == data_from_parent.page_scale_layer)
+    data_for_children.in_subtree_of_page_scale_layer = true;

[ajuma, 2015/12/23 22:17:04]

Nit: How about moving this inside AddTransformNodeIfNeeded (right before we use
this value), since we already have an is_page_scale_layer bool there.

+
   bool created_transform_node = AddTransformNodeIfNeeded(
       data_from_parent, layer, created_render_surface, &data_for_children);
   AddClipNodeIfNeeded(data_from_parent, layer, created_render_surface,
                       created_transform_node, &data_for_children);
 
-  if (layer == data_from_parent.page_scale_layer)
-    data_for_children.in_subtree_of_page_scale_layer = true;
-
   data_for_children.is_hidden =
       layer->hide_layer_and_subtree() || data_from_parent.is_hidden;
   layer->set_is_hidden_from_property_trees(data_for_children.is_hidden);
 
   for (size_t i = 0; i < layer->children().size(); ++i) {
     if (!layer->child_at(i)->scroll_parent()) {
       BuildPropertyTreesInternal(layer->child_at(i), data_for_children);
     } else {
       // The child should be included in its scroll parent's list of scroll
       // children.
@@ skipping 124 matching lines @@
     const gfx::Transform& device_transform,
     PropertyTrees* property_trees) {
   BuildPropertyTreesTopLevelInternal(
       root_layer, page_scale_layer, inner_viewport_scroll_layer,
       outer_viewport_scroll_layer, overscroll_elasticity_layer,
       elastic_overscroll, page_scale_factor, device_scale_factor, viewport,
       device_transform, property_trees);
 }
 
 }  // namespace cc