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 92492afa97d7fdc4e30719125a8cb325a2227f81..f7af27d9e896ac1d68d0b2603beb49711dfb6a9b 100644
--- a/cc/layers/layer.cc
+++ b/cc/layers/layer.cc
@@ -1667,6 +1667,30 @@ 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)

[ajuma, 2016/05/09 16:56:55]

When does this happen? (That is, when does a layer that's getting animation
notifications have an invalid property tree index?)

[jaydasika, 2016/05/10 20:22:29]

In a lot of tests, almost all LayerTreeHostAnimationTests

[ajuma, 2016/05/10 20:46:20]

Ah, this is on Layer, so it might be that we're just starting an animation but
haven't built property trees yet.

+    return;
+
+  if (node->owner_id == id())
+    node->data.is_currently_animating_opacity = is_currently_animating;
+}
+
+void Layer::OnOpacityIsPotentiallyAnimatingChanged(
+    bool has_potential_animation) {
+  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.has_potential_opacity_animation = has_potential_animation;

[ajuma, 2016/05/09 16:56:55]

This also needs to take Layer::OpacityCanAnimateOnImplThread into account (like
property_tree_builder does).

[jaydasika, 2016/05/10 20:22:29]

Done.

+    effect_tree.set_needs_update(true);
+  }
+}
+
 bool Layer::HasActiveAnimationForTesting() const {
   return layer_tree_host_ ? layer_tree_host_->HasActiveAnimationForTesting(this)
                           : false;