Change cc::ElementId to be a uint64_t

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 6b1a1d0bcc0f671abf75f631a29b83f040b0c767..529e91163719f5bbf0825fd95227353be92b0c43 100644
--- a/cc/layers/layer_impl.cc
+++ b/cc/layers/layer_impl.cc
@@ -627,12 +627,11 @@ const gfx::Transform& LayerImpl::Transform() const {
 }
 
 void LayerImpl::SetElementId(ElementId element_id) {
-  if (element_id == element_id_)
+  if (element_id.id == element_id_.id)
     return;
 
   TRACE_EVENT1(TRACE_DISABLED_BY_DEFAULT("compositor-worker"),
-               "LayerImpl::SetElementId", "element",
-               element_id.AsValue().release());
+               "LayerImpl::SetElementId", "element", element_id.id);
 
   layer_tree_impl_->RemoveFromElementMap(this);
   element_id_ = element_id;
@@ -799,7 +798,7 @@ void LayerImpl::AsValueInto(base::trace_event::TracedValue* state) const {
                     base::saturated_cast<int>(GPUMemoryUsageInBytes()));
 
   if (element_id_)
-    element_id_.AddToTracedValue(state);
+    state->SetInteger("element_id", element_id_.id);
 
   if (mutable_properties_ != MutableProperty::kNone)
     state->SetInteger("mutable_properties", mutable_properties_);