Redirect references from control_flow_ops.cond to cond.cond.

This is to ultimately remove the circular dependencies that pass from `control_flow_ops.py` to `cond_v2.py`.

PiperOrigin-RevId: 518458725

Author: fionalang

tensorflow_model_optimization/python/core/keras/BUILD

@@ -41,7 +41,7 @@ py_strict_library(
     srcs_version = "PY3",
     visibility = ["//visibility:public"],
     deps = [
-        # python:control_flow_ops tensorflow dep2,
+        # tensorflow dep1,
         # python:smart_cond tensorflow dep2,
         # python:variables tensorflow dep2,
     ],

tensorflow_model_optimization/python/core/keras/utils.py

@@ -22,9 +22,10 @@
 from __future__ import division
 from __future__ import print_function
 
+import tensorflow as tf
+
 # TODO(b/151772467): Move away from depending on private APIs.
 from tensorflow.python.framework import smart_cond as smart_module
-from tensorflow.python.ops import control_flow_ops
 from tensorflow.python.ops import variables
 
 
@@ -48,7 +49,7 @@ def smart_cond(pred, true_fn=None, false_fn=None, name=None):  # pylint: disable
     TypeError: If `true_fn` or `false_fn` is not callable.
   """
   if isinstance(pred, variables.Variable):
-    return control_flow_ops.cond(
+    return tf.cond(
         pred, true_fn=true_fn, false_fn=false_fn, name=name)
   return smart_module.smart_cond(
       pred, true_fn=true_fn, false_fn=false_fn, name=name)