Change cc::ElementId to be a uint64_t

cc/trees/scroll_node.cc

Index: cc/trees/scroll_node.cc
diff --git a/cc/trees/scroll_node.cc b/cc/trees/scroll_node.cc
index 050dbf00294a9e283da0a5752a7a38c8f6a95127..1653c596a31fd4184f86717cdd6ec0dbc8dffdb8 100644
--- a/cc/trees/scroll_node.cc
+++ b/cc/trees/scroll_node.cc
@@ -25,6 +25,7 @@ ScrollNode::ScrollNode()
       should_flatten(false),
       user_scrollable_horizontal(false),
       user_scrollable_vertical(false),
+      element_id(kInvalidElementId),
       transform_id(0) {}
 
 ScrollNode::ScrollNode(const ScrollNode& other) = default;
@@ -62,7 +63,7 @@ void ScrollNode::AsValueInto(base::trace_event::TracedValue* value) const {
   value->SetBoolean("user_scrollable_horizontal", user_scrollable_horizontal);
   value->SetBoolean("user_scrollable_vertical", user_scrollable_vertical);
 
-  element_id.AddToTracedValue(value);
+  value->SetInteger("element_id", element_id);
   value->SetInteger("transform_id", transform_id);
 }