cc : Track ids for which active opacity always wins on property trees

cc/trees/property_tree.h

Index: cc/trees/property_tree.h
diff --git a/cc/trees/property_tree.h b/cc/trees/property_tree.h
index 96a2f441907028d599cdc19333ad05da8f48ff67..2b5e47d907f41a088a0053a1f28aa26a7f6a60b0 100644
--- a/cc/trees/property_tree.h
+++ b/cc/trees/property_tree.h
@@ -675,6 +675,8 @@ class CC_EXPORT PropertyTrees final {
   std::unordered_map<int, int> effect_id_to_index_map;
   std::unordered_map<int, int> clip_id_to_index_map;
   std::unordered_map<int, int> scroll_id_to_index_map;
+
+  std::vector<int> always_use_active_tree_opacity_effect_ids;
   TransformTree transform_tree;
   EffectTree effect_tree;
   ClipTree clip_tree;
@@ -700,6 +702,7 @@ class CC_EXPORT PropertyTrees final {
   void SetInnerViewportContainerBoundsDelta(gfx::Vector2dF bounds_delta);
   void SetOuterViewportContainerBoundsDelta(gfx::Vector2dF bounds_delta);
   void SetInnerViewportScrollBoundsDelta(gfx::Vector2dF bounds_delta);
+  void PushOpacityIfNeeded(PropertyTrees* target_tree);
   void UpdateChangeTracking();
   void PushChangeTrackingTo(PropertyTrees* tree);
   void ResetAllChangeTracking(ResetFlags flag);