cc : Compute subtree has copy requests before property tree building

cc/trees/draw_property_utils.cc

Index: cc/trees/draw_property_utils.cc
diff --git a/cc/trees/draw_property_utils.cc b/cc/trees/draw_property_utils.cc
index 27eb425da9995d22ce9b3ac02f1f37b16c99cbdf..def7acef37bf1d26f1a09f4319d52b80c9f74ecf 100644
--- a/cc/trees/draw_property_utils.cc
+++ b/cc/trees/draw_property_utils.cc
@@ -458,8 +458,7 @@ static inline bool LayerShouldBeSkippedInternal(
       transform_tree.Node(layer->transform_tree_index());
   const EffectNode* effect_node = effect_tree.Node(layer->effect_tree_index());
 
-  if (effect_node->has_render_surface &&
-      effect_node->num_copy_requests_in_subtree > 0)
+  if (effect_node->has_render_surface && effect_node->subtree_has_copy_request)

[weiliangc, 2017/04/19 17:58:48]

If subtree_has_copy_request is only useful here, why not just update the value
right before calling LayerShouldBeSkipped in FindLayersThatNeedUpdates? That way
we don't need to care about keep track of it during property tree builder?

[jaydasika, 2017/04/19 18:15:14]

I want to stop creating effect nodes for handling SetHideLayerAndSubtree
(https://bugs.chromium.org/p/chromium/issues/detail?id=595843#c5). To do that,
we will need to know subtree_has_copy_request during property tree building as
we have to create effects nodes in case copy requests exist. So, this CL is to
make that possible.

[weiliangc, 2017/04/19 21:21:54]

If we want to avoid sending those layers over, could we ignore them while
building layer list/property trees? and is it possible to not have
subtree_has_copy_request value in the node in the future?

[jaydasika, 2017/04/19 21:31:36]

Yes, that's the plan I have in mind : skip these layers while property tree
building and don't send them at commit so LayerImpl::layer_list won't have them.
I think it should be possible to delete effect node's subtree_has_copy_request.

     return false;
   // If the layer transform is not invertible, it should be skipped.
   // TODO(ajuma): Correctly process subtrees with singular transform for the