cc: Make DamageTracker use the effect tree and layer list

cc/layers/effect_tree_layer_list_iterator.cc

 // Copyright 2017 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/layers/effect_tree_layer_list_iterator.h"
 
 namespace cc {
 
 EffectTreeLayerListIterator::EffectTreeLayerListIterator(
     LayerTreeImpl* layer_tree_impl)
@@ skipping 25 matching lines @@
     next_effect_tree_index_ = current_effect_tree_index_;
     lowest_common_effect_tree_ancestor_index_ = current_effect_tree_index_;
   }
 }
 
 EffectTreeLayerListIterator::EffectTreeLayerListIterator(
     const EffectTreeLayerListIterator& iterator) = default;
 
 EffectTreeLayerListIterator::~EffectTreeLayerListIterator() {}
 
-// Finds the lowest common ancestor that has a render surface.
-static int LowestCommonAncestor(int effect_id_1,
-                                int effect_id_2,
-                                const EffectTree* effect_tree) {
-  while (effect_id_1 != effect_id_2) {
-    if (effect_id_1 < effect_id_2)
-      effect_id_2 = effect_tree->Node(effect_id_2)->target_id;
-    else
-      effect_id_1 = effect_tree->Node(effect_id_1)->target_id;
-  }
-
-  return effect_id_1;
-}
-
 void EffectTreeLayerListIterator::operator++() {
   switch (state_) {
     case State::LAYER:
       // Find the next drawn layer.
       layer_list_iterator_++;
       while (layer_list_iterator_ != layer_tree_impl_->rend() &&
              !(*layer_list_iterator_)
                   ->is_drawn_render_surface_layer_list_member()) {
         layer_list_iterator_++;
       }
       if (layer_list_iterator_ == layer_tree_impl_->rend()) {
         next_effect_tree_index_ = EffectTree::kInvalidNodeId;
         lowest_common_effect_tree_ancestor_index_ = EffectTree::kInvalidNodeId;
         state_ = State::TARGET_SURFACE;
         break;
       }
 
       next_effect_tree_index_ =
           (*layer_list_iterator_)->render_target_effect_tree_index();
 
       // If the next drawn layer has a different target effect tree index, check
       // for surfaces whose contributors have all been visited.
       if (next_effect_tree_index_ != current_effect_tree_index_) {
-        lowest_common_effect_tree_ancestor_index_ = LowestCommonAncestor(
-            current_effect_tree_index_, next_effect_tree_index_, effect_tree_);
+        lowest_common_effect_tree_ancestor_index_ =
+            effect_tree_->LowestCommonAncestorWithRenderSurface(
+                current_effect_tree_index_, next_effect_tree_index_);
         // If the current layer's target effect node is an ancestor of the next
         // layer's target effect node, then the current effect node still has
         // more contributors that need to be visited. Otherwise, all
         // contributors have been visited, so we visit the node's surface next.
         if (current_effect_tree_index_ ==
             lowest_common_effect_tree_ancestor_index_) {
           current_effect_tree_index_ = next_effect_tree_index_;
           lowest_common_effect_tree_ancestor_index_ = next_effect_tree_index_;
         } else {
           state_ = State::TARGET_SURFACE;
@@ skipping 35 matching lines @@
         // surface.
         state_ = State::TARGET_SURFACE;
       }
       break;
     case State::END:
       NOTREACHED();
   }
 }
 
 }  // namespace cc