[tf.data] Deprecate `tf.contrib.data` and introduce `tf.data.experimental` to replace it.

This change prepares `tf.data` for TensorFlow 2.0, where `tf.contrib` will no longer exist. It retains the pre-existing endpoints in `tf.contrib.data` with deprecation warnings.

Note there are some exceptions to the move:

* Deprecated symbols in `tf.contrib.data` have not been moved to `tf.data.experimental`, because replacements already exist.
* `tf.contrib.data.LMDBDataset` has not been moved, because we plan to move it to a SIG-maintained repository.
* `tf.contrib.data.assert_element_shape()` has not yet been moved, because it depends on functionality in `tf.contrib`, and it will move in a later change.
* `tf.contrib.data.AUTOTUNE` has not yet been moved, because we have not yet determined how to `tf_export()` a Python integer.
* The stats-related API endpoints have not yet appeared in a released version of TensorFlow, so these are moved to `tf.data.experimental` without retaining an endpoint in `tf.contrib.data`.

In addition, this change includes some build rule and ApiDef refactoring:
* Some of the "//third_party/tensorflow/python:training" dependencies had to be split in order to avoid a circular dependency.
* The `tf.contrib.stateless` ops now have a private core library for the generated wrappers (and accordingly are hidden in their ApiDef) so that `tf.data.experimental.sample_from_datasets()` can depend on them.

PiperOrigin-RevId: 215304249

1 files changed, 34 insertions, 0 deletions

diff --git a/tensorflow/python/BUILD b/tensorflow/python/BUILD
index 9275ad767e..fe81254ef7 100644
--- a/tensorflow/python/BUILD
+++ b/tensorflow/python/BUILD
@@ -1740,6 +1740,14 @@ tf_gen_op_wrapper_private_py(
 )
 
 tf_gen_op_wrapper_private_py(
+    name = "stateless_random_ops_gen",
+    visibility = [
+        "//tensorflow/contrib/stateless:__pkg__",
+        "//tensorflow/python/data/experimental/ops:__pkg__",
+    ],
+)
+
+tf_gen_op_wrapper_private_py(
     name = "list_ops_gen",
 )
 
@@ -3302,9 +3310,11 @@ py_library(
             "training/checkpointable/**/*.py",
             # The following targets have their own build rules (same name as the
             # file):
+            "training/basic_session_run_hooks.py",
             "training/checkpoint_management.py",
             "training/saveable_object.py",
             "training/saver.py",
+            "training/session_run_hook.py",
             "training/training_util.py",
         ],
     ),
@@ -3312,6 +3322,7 @@ py_library(
     deps = [
         ":array_ops",
         ":array_ops_gen",
+        ":basic_session_run_hooks",
         ":checkpoint_management",
         ":checkpoint_ops_gen",
         ":client",
@@ -3336,6 +3347,7 @@ py_library(
         ":saver",
         ":sdca_ops",
         ":session",
+        ":session_run_hook",
         ":sparse_ops",
         ":sparse_tensor",
         ":state_ops",
@@ -3380,6 +3392,28 @@ py_library(
 )
 
 py_library(
+    name = "session_run_hook",
+    srcs = ["training/session_run_hook.py"],
+    srcs_version = "PY2AND3",
+    deps = [":util"],
+)
+
+py_library(
+    name = "basic_session_run_hooks",
+    srcs = ["training/basic_session_run_hooks.py"],
+    srcs_version = "PY2AND3",
+    deps = [
+        ":client",
+        ":framework",
+        ":platform",
+        ":protos_all_py",
+        ":session_run_hook",
+        ":training_util",
+        ":util",
+    ],
+)
+
+py_library(
     name = "saver",
     srcs = ["training/saver.py"],
     srcs_version = "PY2AND3",