Clarify property tree id-to-index map names.

cc/input/scrollbar_animation_controller_linear_fade.cc

Index: cc/input/scrollbar_animation_controller_linear_fade.cc
diff --git a/cc/input/scrollbar_animation_controller_linear_fade.cc b/cc/input/scrollbar_animation_controller_linear_fade.cc
index ee7f4afe64827fbbf46c91fba0a111a6c925cfb8..09ec511aca530d1fd7081a330cb98f2c09b375c2 100644
--- a/cc/input/scrollbar_animation_controller_linear_fade.cc
+++ b/cc/input/scrollbar_animation_controller_linear_fade.cc
@@ -63,7 +63,8 @@ void ScrollbarAnimationControllerLinearFade::ApplyOpacityToScrollbars(
     PropertyTrees* property_trees =
         scrollbar->layer_tree_impl()->property_trees();
     // If this method is called during LayerImpl::PushPropertiesTo, we may not
-    // yet have valid effect_id_to_index_map entries as property trees are
+    // yet have valid layer_id_to_effect_node_index entries as property trees
+    // are

[ajuma, 2017/01/10 00:51:44]

nit: needs re-wrapping

[wkorman, 2017/01/10 01:13:43]

Done.

     // pushed after layers during activation. We can skip updating opacity in
     // that case as we are only registering a scrollbar and because opacity will
     // be overwritten anyway when property trees are pushed.
@@ -71,7 +72,7 @@ void ScrollbarAnimationControllerLinearFade::ApplyOpacityToScrollbars(
                                          scrollbar->id())) {
       property_trees->effect_tree.OnOpacityAnimated(
           scrollbar->CanScrollOrientation() ? opacity : 0,
-          property_trees->effect_id_to_index_map[scrollbar->id()],
+          property_trees->layer_id_to_effect_node_index[scrollbar->id()],
           scrollbar->layer_tree_impl());
     }
   }