cc:: Remove RenderSurfaceImpl::TargetEffectTreeIndex

cc/trees/draw_property_utils.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/draw_property_utils.h"
 
 #include <stddef.h>
 
 #include <vector>
 
@@ skipping 897 matching lines @@
   float draw_opacity = 1.f;
   while (node != target_node) {
     draw_opacity *= node->data.opacity;
     node = tree.parent(node);
   }
   return draw_opacity;
 }
 
 static float SurfaceDrawOpacity(RenderSurfaceImpl* render_surface,
                                 const EffectTree& tree) {
+  // Draw opacity of a surface is the product of opacities between the surface
+  // (included) and its target surface (excluded).
   const EffectNode* node = tree.Node(render_surface->EffectTreeIndex());
-  float target_opacity_tree_index = render_surface->TargetEffectTreeIndex();
-  if (target_opacity_tree_index < 0)
-    return node->data.screen_space_opacity;
-  const EffectNode* target_node = tree.Node(target_opacity_tree_index);
-  float draw_opacity = 1.f;
-  while (node != target_node) {
+  float draw_opacity = node->data.opacity;
+  for (node = tree.parent(node); node && !node->data.has_render_surface;
+       node = tree.parent(node)) {
     draw_opacity *= node->data.opacity;
-    node = tree.parent(node);
   }
   return draw_opacity;
 }
 
 static bool LayerCanUseLcdText(const LayerImpl* layer,
                                bool layers_always_allowed_lcd_text,
                                bool can_use_lcd_text,
                                const TransformNode* transform_node,
                                const EffectNode* effect_node) {
   if (layers_always_allowed_lcd_text)
@@ skipping 241 matching lines @@
 
 void UpdateElasticOverscrollInPropertyTrees(
     PropertyTrees* property_trees,
     const Layer* overscroll_elasticity_layer,
     const gfx::Vector2dF& elastic_overscroll) {
   UpdateElasticOverscrollInPropertyTreesInternal(
       property_trees, overscroll_elasticity_layer, elastic_overscroll);
 }
 
 }  // namespace cc