cc : Track opacity animation changes on effect tree

cc/layers/layer.cc

Index: cc/layers/layer.cc
diff --git a/cc/layers/layer.cc b/cc/layers/layer.cc
index 88f2036fc8038144880d9942efe97e02a48f7b59..076f44e8f4df53dcefb23520236c37d9215ec91a 100644
--- a/cc/layers/layer.cc
+++ b/cc/layers/layer.cc
@@ -1668,6 +1668,17 @@ void Layer::OnTransformIsPotentiallyAnimatingChanged(bool is_animating) {
   }
 }
 
+void Layer::OnOpacityIsCurrentlyAnimatingChanged(bool is_currently_animating) {
+  DCHECK(layer_tree_host_);
+  EffectTree& effect_tree = layer_tree_host_->property_trees()->effect_tree;
+  EffectNode* node = effect_tree.Node(effect_tree_index());
+  if (!node)
+    return;
+
+  if (node->owner_id == id())
+    node->data.is_currently_animating_opacity = is_currently_animating;
+}
+
 bool Layer::HasActiveAnimationForTesting() const {
   return layer_tree_host_ ? layer_tree_host_->HasActiveAnimationForTesting(this)
                           : false;