Clarify property tree id-to-index map names.

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 430 matching lines @@
       node.clip_type = ClipNode::ClipType::APPLIES_LOCAL_CLIP;
     else
       node.clip_type = ClipNode::ClipType::NONE;
     node.resets_clip = has_unclipped_surface;
     node.layers_are_clipped = layers_are_clipped;
     node.layers_are_clipped_when_surfaces_disabled =
         layers_are_clipped_when_surfaces_disabled;
 
     data_for_children->clip_tree_parent =
         data_for_children->property_trees->clip_tree.Insert(node, parent_id);
-    data_for_children->property_trees->clip_id_to_index_map[layer->id()] =
+    data_for_children->property_trees
+        ->layer_id_to_clip_node_index[layer->id()] =
         data_for_children->clip_tree_parent;
   }
 
   layer->SetClipTreeIndex(data_for_children->clip_tree_parent);
 }
 
 static inline int SortingContextId(Layer* layer) {
   return layer->sorting_context_id();
 }
 
@@ skipping 150 matching lines @@
     layer->SetTransformTreeIndex(parent_index);
     return false;
   }
 
   data_for_children->property_trees->transform_tree.Insert(TransformNode(),
                                                            parent_index);
 
   TransformNode* node =
       data_for_children->property_trees->transform_tree.back();
   layer->SetTransformTreeIndex(node->id);
-  data_for_children->property_trees->transform_id_to_index_map[layer->id()] =
-      node->id;
+  data_for_children->property_trees
+      ->layer_id_to_transform_node_index[layer->id()] = node->id;
 
   node->scrolls = is_scrollable;
   node->should_be_snapped = is_snapped;
   node->flattens_inherited_transform = data_for_children->should_flatten;
 
   node->sorting_context_id = SortingContextId(layer);
 
   if (layer == data_from_ancestor.page_scale_layer)
     data_for_children->in_subtree_of_page_scale_layer = true;
   node->in_subtree_of_page_scale_layer =
@@ skipping 451 matching lines @@
     // Root render surface acts the unbounded and untransformed to draw content
     // into. Transform node created from root layer (includes device scale
     // factor) and clip node created from root layer (include viewports) applies
     // to root render surface's content, but not root render surface itself.
     node.transform_id = kRootPropertyTreeNodeId;
     node.clip_id = kViewportClipTreeNodeId;
   }
   data_for_children->effect_tree_parent = effect_tree.Insert(node, parent_id);
   int node_id = data_for_children->effect_tree_parent;
   layer->SetEffectTreeIndex(node_id);
-  data_for_children->property_trees->effect_id_to_index_map[layer->id()] =
+  data_for_children->property_trees
+      ->layer_id_to_effect_node_index[layer->id()] =
       data_for_children->effect_tree_parent;
 
   std::vector<std::unique_ptr<CopyOutputRequest>> layer_copy_requests;
   TakeCopyRequests(layer, &layer_copy_requests);
   for (auto& it : layer_copy_requests) {
     effect_tree.AddCopyRequest(node_id, std::move(it));
   }
   layer_copy_requests.clear();
 
   if (should_create_render_surface) {
@@ skipping 66 matching lines @@
     node.element_id = layer->element_id();
     node.transform_id =
         data_for_children->transform_tree_parent->transform_tree_index();
 
     data_for_children->scroll_tree_parent =
         data_for_children->property_trees->scroll_tree.Insert(node, parent_id);
     data_for_children->main_thread_scrolling_reasons =
         node.main_thread_scrolling_reasons;
     data_for_children->scroll_tree_parent_created_by_uninheritable_criteria =
         scroll_node_uninheritable_criteria;
-    data_for_children->property_trees->scroll_id_to_index_map[layer->id()] =
+    data_for_children->property_trees
+        ->layer_id_to_scroll_node_index[layer->id()] =
         data_for_children->scroll_tree_parent;
 
     if (node.scrollable) {
       data_for_children->property_trees->scroll_tree.SetBaseScrollOffset(
           layer->id(), layer->CurrentScrollOffset());
     }
   }
 
   layer->SetScrollTreeIndex(data_for_children->scroll_tree_parent);
 }
@@ skipping 324 matching lines @@
     color = SkColorSetA(color, 255);
   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, color);
   property_trees->ResetCachedData();
 }
 
 }  // namespace cc