Change cc::ElementId to be a uint64_t

cc/trees/layer_tree_host_unittest.cc

Index: cc/trees/layer_tree_host_unittest.cc
diff --git a/cc/trees/layer_tree_host_unittest.cc b/cc/trees/layer_tree_host_unittest.cc
index 5c16a709e2b236e6d8258841b1da23ea0d5f85bc..056eb677f01733398289aa7f772d13fc79f0df04 100644
--- a/cc/trees/layer_tree_host_unittest.cc
+++ b/cc/trees/layer_tree_host_unittest.cc
@@ -1378,7 +1378,9 @@ class LayerTreeHostTestTransformTreeDamageIsUpdated : public LayerTreeHostTest {
     root_->SetBounds(gfx::Size(50, 50));
 
     // Make sure child is registerd for animation.
-    child_->SetElementId(ElementId(2, 0));
+    ElementId element_id;
+    element_id.id = 2;
+    child_->SetElementId(element_id);
 
     // Make sure child and grand_child have transform nodes.
     gfx::Transform rotation;