cc: Use Element Id to Record Animation Changes

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 20e42c99f9c65e42ed9a74bbad0b599f4006f075..c6339adf65780e61b562bc294fd8fe224ec3c31e 100644
--- a/cc/trees/property_tree.h
+++ b/cc/trees/property_tree.h
@@ -104,7 +104,8 @@ class CC_EXPORT PropertyTree {
   }
   T* UpdateNodeFromOwningLayerId(int id) {
     int index = FindNodeIndexFromOwningLayerId(id);
-    if (index == kInvalidNodeId && property_trees()->is_main_thread) {
+    if (index == kInvalidNodeId) {
+      DCHECK(property_trees()->is_main_thread);
       property_trees()->needs_rebuild = true;
     }
 
@@ -171,6 +172,7 @@ class CC_EXPORT TransformTree final : public PropertyTree<TransformNode> {
 
   void clear();
 
+  TransformNode* FindNodeFromElementId(ElementId id);

[wkorman, 2017/03/20 21:59:57]

Sometimes code guidelines prefer naming methods differently rather than relying
on varying return types. I'm actually not sure what Chromium style says here,
thought worth checkpoint for me to learn. Is this ok w/ the one below or should
be have Transform/Effect in the method name for more clarity?

I don't see anything about this explicitly in Chromium/Google C++ style docs.

[weiliangc, 2017/03/21 15:18:52]

Since this is a member function on transform/effect tree, I omitted what node
this function is referring to. I could make FindNodeFromElementId a pure virtual
function on property tree and only override it for transform and effect tree?

[wkorman, 2017/03/21 19:44:23]

Ah, that's right, I think it's ok as is then.

   void OnTransformAnimated(const gfx::Transform& transform,
                            int id,
                            LayerTreeImpl* layer_tree_impl);
@@ -340,6 +342,7 @@ class CC_EXPORT EffectTree final : public PropertyTree<EffectNode> {
 
   void UpdateSurfaceContentsScale(EffectNode* node);
 
+  EffectNode* FindNodeFromElementId(ElementId id);
   void OnOpacityAnimated(float opacity, int id, LayerTreeImpl* layer_tree_impl);
   void OnFilterAnimated(const FilterOperations& filters,
                         int id,