CC Animation: Use ElementId to attach CC animation players.

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 8ae57a16b0d5f9b9f5edbbb63dfcb1383042444b..1c67d69a498f7316c08d120cbb531aa7c5b8d627 100644
--- a/cc/layers/layer_impl.cc
+++ b/cc/layers/layer_impl.cc
@@ -89,6 +89,11 @@ LayerImpl::LayerImpl(LayerTreeImpl* tree_impl, int id)
 
   DCHECK(layer_tree_impl_);
   layer_tree_impl_->RegisterLayer(this);
+  // TODO(loyso): Pass element_id_ via constructor.
+  // Note that since element_id_ is zero here, calling RegisterLayerForElementId
+  // and AddToElementMap is a matter of elegance/symmetry. See SetElementId.
+  if (element_id())
+    layer_tree_impl_->RegisterLayerForElementId(this);
   layer_tree_impl_->AddToElementMap(this);
 
   SetNeedsPushProperties();
@@ -100,10 +105,13 @@ LayerImpl::~LayerImpl() {
   if (!copy_requests_.empty() && layer_tree_impl_->IsActiveTree())
     layer_tree_impl()->RemoveLayerWithCopyOutputRequest(this);
   layer_tree_impl_->UnregisterScrollLayer(this);
-  layer_tree_impl_->UnregisterLayer(this);
-  layer_tree_impl_->RemoveLayerShouldPushProperties(this);
 
   layer_tree_impl_->RemoveFromElementMap(this);
+  if (element_id())
+    layer_tree_impl_->UnregisterLayerForElementId(this);
+  layer_tree_impl_->UnregisterLayer(this);
+
+  layer_tree_impl_->RemoveLayerShouldPushProperties(this);
 
   TRACE_EVENT_OBJECT_DELETED_WITH_ID(
       TRACE_DISABLED_BY_DEFAULT("cc.debug"), "cc::LayerImpl", this);
@@ -389,7 +397,13 @@ void LayerImpl::SetScrollClipLayer(int scroll_clip_layer_id) {
     return;
 
   layer_tree_impl()->UnregisterScrollLayer(this);
+  if (element_id())
+    layer_tree_impl()->UnregisterLayerForElementId(this);
+
   scroll_clip_layer_id_ = scroll_clip_layer_id;
+
+  if (element_id())
+    layer_tree_impl()->RegisterLayerForElementId(this);
   layer_tree_impl()->RegisterScrollLayer(this);
 }
 
@@ -1023,8 +1037,15 @@ void LayerImpl::SetElementId(ElementId element_id) {
                "LayerImpl::SetElementId", "id", element_id);
 
   layer_tree_impl_->RemoveFromElementMap(this);
+  if (element_id_)
+    layer_tree_impl_->UnregisterLayerForElementId(this);
+
   element_id_ = element_id;
+
   layer_tree_impl_->AddToElementMap(this);
+  if (element_id_)
+    layer_tree_impl_->RegisterLayerForElementId(this);
+
   SetNeedsPushProperties();
 }