Change cc::ElementId to be a uint64_t

cc/layers/layer.cc

Index: cc/layers/layer.cc
diff --git a/cc/layers/layer.cc b/cc/layers/layer.cc
index 2c2bb97f40ba055cdca1d6c2c2c92f79a57e94bd..166dc02bbd5e5e115f9c6f76711ac72fb1f01bea 100644
--- a/cc/layers/layer.cc
+++ b/cc/layers/layer.cc
@@ -124,7 +124,7 @@ void Layer::SetLayerTreeHost(LayerTreeHost* host) {
     layer_tree_host_->property_trees()->RemoveIdFromIdToIndexMaps(id());
     layer_tree_host_->property_trees()->needs_rebuild = true;
     layer_tree_host_->UnregisterLayer(this);
-    if (inputs_.element_id) {
+    if (inputs_.element_id.id) {
       layer_tree_host_->UnregisterElement(inputs_.element_id,
                                           ElementListType::ACTIVE, this);
     }
@@ -1422,18 +1422,18 @@ void Layer::RunMicroBenchmark(MicroBenchmark* benchmark) {
   benchmark->RunOnLayer(this);
 }
 
-void Layer::SetElementId(ElementId id) {
+void Layer::SetElementId(ElementId element_id) {
   DCHECK(IsPropertyChangeAllowed());
-  if (inputs_.element_id == id)
+  if (inputs_.element_id == element_id)
     return;
   TRACE_EVENT1(TRACE_DISABLED_BY_DEFAULT("compositor-worker"),
-               "Layer::SetElementId", "element", id.AsValue().release());
+               "Layer::SetElementId", "element", element_id.id);
   if (inputs_.element_id && layer_tree_host()) {
     layer_tree_host_->UnregisterElement(inputs_.element_id,
                                         ElementListType::ACTIVE, this);
   }
 
-  inputs_.element_id = id;
+  inputs_.element_id = element_id;
 
   if (inputs_.element_id && layer_tree_host()) {
     layer_tree_host_->RegisterElement(inputs_.element_id,