Remove owning_id from EffectNode and replace it by an opaque stable_id

cc/layers/layer_impl.cc

Index: cc/layers/layer_impl.cc
diff --git a/cc/layers/layer_impl.cc b/cc/layers/layer_impl.cc
index 1399bb9c6834c3ed8ee34097b5a8137f867cd682..0fe39229c157e35c2c30a565621e9458ea7258b1 100644
--- a/cc/layers/layer_impl.cc
+++ b/cc/layers/layer_impl.cc
@@ -403,7 +403,6 @@ std::unique_ptr<base::DictionaryValue> LayerImpl::LayerTreeAsJson() {
 
   result->SetBoolean("DrawsContent", draws_content_);
   result->SetBoolean("Is3dSorted", Is3dSorted());
-  result->SetDouble("OPACITY", Opacity());
   result->SetBoolean("ContentsOpaque", contents_opaque_);
 
   if (scrollable())
@@ -614,13 +613,6 @@ void LayerImpl::SetContentsOpaque(bool opaque) {
   contents_opaque_ = opaque;
 }
 
-float LayerImpl::Opacity() const {
-  if (const EffectNode* node = GetEffectTree().FindNodeFromOwningLayerId(id()))
-    return node->opacity;
-  else
-    return 1.f;
-}
-
 const gfx::Transform& LayerImpl::Transform() const {
   DCHECK_NE(GetTransformTree().FindNodeFromOwningLayerId(id()), nullptr);
   return GetTransformTree().FindNodeFromOwningLayerId(id())->local;
@@ -795,8 +787,6 @@ void LayerImpl::AsValueInto(base::trace_event::TracedValue* state) const {
   state->SetInteger("layer_id", id());
   MathUtil::AddToTracedValue("bounds", bounds_, state);
 
-  state->SetDouble("opacity", Opacity());
-
   MathUtil::AddToTracedValue("position", position_, state);
 
   state->SetInteger("draws_content", DrawsContent());