cc: Main thread skip single layers instead of subtrees

cc/trees/property_tree_builder.cc

Index: cc/trees/property_tree_builder.cc
diff --git a/cc/trees/property_tree_builder.cc b/cc/trees/property_tree_builder.cc
index 7b4300b9fab6c98ffa833d4eae1f6481e0cba1bd..78d7624d766b372092054e4841c1293d722d551c 100644
--- a/cc/trees/property_tree_builder.cc
+++ b/cc/trees/property_tree_builder.cc
@@ -632,6 +632,9 @@ bool AddEffectNodeIfNeeded(
         node.data.has_background_filters;
     node.data.to_screen_opacity_is_animated =
         parent_node->data.to_screen_opacity_is_animated || has_animated_opacity;
+    node.data.to_screen_opacity_can_animate_on_impl =
+        parent_node->data.to_screen_opacity_can_animate_on_impl &&
+        layer->OpacityCanAnimateOnImplThread();

[ajuma, 2016/04/06 19:49:29]

I believe to_screen_opacity_is_animated already accounts for this, so this
shouldn't be needed (see the definition of IsAnimatingOpacity, which is used to
compute has_animated_opacity).

[sunxd, 2016/04/07 15:37:13]

Done.

   } else {
     // Root render surface acts the unbounded and untransformed to draw content
     // into. Transform node created from root layer (includes device scale
@@ -642,6 +645,8 @@ bool AddEffectNodeIfNeeded(
     node.data.node_or_ancestor_has_background_filters =
         node.data.has_background_filters;
     node.data.to_screen_opacity_is_animated = has_animated_opacity;
+    node.data.to_screen_opacity_can_animate_on_impl =
+        layer->OpacityCanAnimateOnImplThread();
   }
   node.data.target_id =
       should_create_render_surface