message: Remove accidentally tracked attributes and fix deferred save counter dependency.
  The new attributes added in cl/326701488 added the save counter variable dependency, causing `assert_existing_objects_matched` to fail when it shouldn't.
diff: @@ -1908,8 +1908,9 @@ class Checkpoint(tracking.AutoTrackable):
  kwargs["root"] = root
  root._maybe_initialize_trackable()
  - self._save_counter = root._lookup_dependency("save_counter")
  - self._root = root
  + self._save_counter = data_structures.NoDependency(
  + root._lookup_dependency("save_counter"))
  + self._root = data_structures.NoDependency(root)
  for k, v in sorted(kwargs.items(), key=lambda item: item[0]):
  setattr(self, k, v)
  @@ -1930,7 +1931,8 @@ class Checkpoint(tracking.AutoTrackable):
  "root.{name} already exists.".format(name=k))
  self._saver = saver_with_op_caching(saver_root, attached_dependencies)
  - self._attached_dependencies = attached_dependencies
  + self._attached_dependencies = data_structures.NoDependency(
  + attached_dependencies)
  def _maybe_create_save_counter(self):
  """Create a save counter if it does not yet exist."""
  @@ -1952,7 +1954,7 @@ class Checkpoint(tracking.AutoTrackable):
  # When loading a checkpoint, the save counter is created after
  # the checkpoint has been loaded, so it must be handled in a deferred
  # manner.
  - restore = self.root._deferred_dependencies.get("save_counter") # pylint: disable=protected-access
  + restore = self.root._deferred_dependencies.pop("save_counter", ()) # pylint: disable=protected-access
  if restore:
  restore[0].restore(self._save_counter)
  