Revert "Refactor case and case_v2 out of control_flow_ops.py."

This reverts commit 50b80fb.

Author: jburnim

tensorflow_probability/python/internal/prefer_static.py

@@ -27,7 +27,7 @@
 
 from tensorflow.python.framework import ops  # pylint: disable=g-direct-tensorflow-import
 from tensorflow.python.framework import tensor_util  # pylint: disable=g-direct-tensorflow-import
-from tensorflow.python.ops import control_flow_case  # pylint: disable=g-direct-tensorflow-import
+from tensorflow.python.ops import control_flow_ops  # pylint: disable=g-direct-tensorflow-import
 from tensorflow.python.util import tf_inspect  # pylint: disable=g-direct-tensorflow-import
 
 JAX_MODE = False
@@ -286,13 +286,8 @@ def maybe_static(pred):
         return pred
       return p
     pred_fn_pairs = [(maybe_static(pred), fn) for pred, fn in pred_fn_pairs]
-  return control_flow_case._case_helper(  # pylint: disable=protected-access
-      cond,
-      pred_fn_pairs,
-      default,
-      exclusive,
-      name,
-      allow_python_preds=True)
+  return control_flow_ops._case_helper(  # pylint: disable=protected-access
+      cond, pred_fn_pairs, default, exclusive, name, allow_python_preds=True)
 
 
 def size0(x, name=None):

tensorflow_probability/substrates/meta/rewrite.py

@@ -70,9 +70,9 @@
     'from tensorflow.python.ops import parallel_for':
         'from tensorflow_probability.python.internal.backend.numpy '
         'import functional_ops as parallel_for',
-    'from tensorflow.python.ops import control_flow_case':
+    'from tensorflow.python.ops import control_flow_ops':
         'from tensorflow_probability.python.internal.backend.numpy '
-        'import control_flow as control_flow_case',
+        'import control_flow as control_flow_ops',
     ('from tensorflow.python.saved_model '
      'import nested_structure_coder'):
         ('from tensorflow_probability.python.internal.backend.numpy '