Remove use of deprecated `_checkpoint_dependencies`.

PiperOrigin-RevId: 439431826
diff --git a/tensorflow/python/training/tracking/data_structures_test.py b/tensorflow/python/training/tracking/data_structures_test.py
index 76ab714..76b637b 100644
--- a/tensorflow/python/training/tracking/data_structures_test.py
+++ b/tensorflow/python/training/tracking/data_structures_test.py
@@ -182,7 +182,7 @@
     m.l = [1, 2]
     m.l.insert(0, 0)
     self.assertEqual(m.l, [0, 1, 2])
-    self.assertEqual(m.l._checkpoint_dependencies, [])
+    self.assertEqual(m.l._trackable_children(), {})
 
   def testFunctionCaching(self):
     @def_function.function
@@ -272,7 +272,7 @@
     l[:] = 2, 8, 9, 0
     self.assertEqual(l, [2, 8, 9, 0])
     l._maybe_initialize_trackable()  # pylint: disable=protected-access
-    self.assertEqual(len(l._checkpoint_dependencies), 0)  # pylint: disable=protected-access
+    self.assertEqual(len(l._trackable_children()), 0)  # pylint: disable=protected-access
 
   def testSetSlice_cannotSaveIfTrackableModified(self):
     v1 = resource_variable_ops.ResourceVariable(1.)
@@ -301,14 +301,14 @@
   def testIMulPositive(self):
     v = variables.Variable(1.)
     l = data_structures.ListWrapper([1, 2, 3, 4, v])
-    self.assertEqual([("4", v)], l._checkpoint_dependencies)
+    self.assertDictEqual({"4": v}, l._trackable_children())
     root = util.Checkpoint(l=l)
     prefix = os.path.join(self.get_temp_dir(), "ckpt")
     path = root.save(prefix)
     v.assign(5.)
     l *= 2
     self.assertEqual(l, [1, 2, 3, 4, v, 1, 2, 3, 4, v])
-    self.assertEqual([("4", v), ("9", v)], l._checkpoint_dependencies)
+    self.assertDictEqual({"4": v, "9": v}, l._trackable_children())
     root.restore(path)
     self.assertAllClose(1., v.numpy())
 
@@ -607,7 +607,7 @@
     self.assertIs(v, m.nt.x)
     self.assertIs(v, m.nt[0])
     self.assertIs(
-        v, m._checkpoint_dependencies[0].ref._checkpoint_dependencies[0].ref)
+        v, m._trackable_children()["nt"]._trackable_children()["x"])
     self.assertEqual(2, m.nt.y)
 
   def testNamedTupleConflictingAttributes(self):
@@ -637,10 +637,10 @@
     m.nt = nt
     self.assertEqual(3, m.nt.y)
     self.assertIs(v, m.nt.x)
-    self.assertIs(
-        v, m._checkpoint_dependencies[0].ref._checkpoint_dependencies[0].ref)
-    self.assertEqual("x", m.nt._checkpoint_dependencies[0].name)
-    self.assertEqual("0", m.nt._checkpoint_dependencies[1].name)
+    self.assertIn(v,
+                  m._trackable_children()["nt"]._trackable_children().values())
+    self.assertIn("x", m.nt._trackable_children())
+    self.assertIn("0", m.nt._trackable_children())
     self.assertEqual(5, self.evaluate(m.nt.summed))
 
   def testUnnamedSubclassing(self):
@@ -655,8 +655,8 @@
     unt = UnnamedSubclass([v, 2])
     m = module.Module()
     m.unt = unt
-    self.assertEqual("0", m.unt._checkpoint_dependencies[0].name)
-    self.assertLen(m.unt._checkpoint_dependencies, 1)
+    self.assertIn("0", m.unt._trackable_children())
+    self.assertLen(m.unt._trackable_children(), 1)
     self.assertEqual(4, self.evaluate(m.unt.summed))
     nest.assert_same_structure(
         [m.unt], nest.map_structure(lambda x: x, [m.unt]))
@@ -744,9 +744,9 @@
   def testLoopAssignedModule(self):
     m = module.Module()
     m.s = (m,)
-    self.assertLen(m._checkpoint_dependencies, 1)
-    self.assertIs(m.s, m._checkpoint_dependencies[0].ref)
-    self.assertIs("s", m._checkpoint_dependencies[0].name)
+    self.assertLen(m._trackable_children(), 1)
+    self.assertIn("s", m._trackable_children())
+    self.assertIs(m.s, m._trackable_children()["s"])
     self.assertEqual((), m.trainable_variables)