Create a version of frozen keras in TF.

This will be serving as dependency for other legacy TF high level API
like tf.layers and feature column etc.

This change also removes the mixed precision API, which v1 API shouldn't rely on. We might remove more features from the layer in follow up cls, eg distribution strategy, etc. This will help reduce the scope of python code that will be copied.

PiperOrigin-RevId: 299201999
Change-Id: Idd5bc851fcb76116b5b66cfb8dddab6e8087b3e0

tensorflow/python/frozen_keras/README.md

@@ -0,0 +1,15 @@
+# DO NOT USE
+
+Everything under this package is for internal usage, and only serves a
+dependency from legacy TF v1 APIs that relies on Keras. Any active development
+should happen in third_party/tensorflow/python/keras instead.
+
+## Background
+
+In order to build a more modular Tensorflow and Keras, we decided to split the
+Keras code into its own repository. Having TensorFlow depend on
+Keras is a red flag as it is a reverse dependency. As some legacy TF V1 APIs
+are using Keras classes as base classes, like `Layer`, we decided to keep a copy
+of the trimmed Keras code to resolve the reverse dependency. This will also
+ensure the stability of the TF V1 API will be not affected by the active
+development of the Keras project.

tensorflow/python/frozen_keras/engine/BUILD

@@ -0,0 +1,73 @@
+load("//tensorflow:tensorflow.bzl", "tf_py_test")
+
+package(
+    default_visibility = ["//tensorflow:__subpackages__"],
+    licenses = ["notice"],  # Apache 2.0
+)
+
+py_library(
+    name = "legacy_base_layer",
+    srcs = ["legacy_base_layer.py"],
+    deps = [
+        "//tensorflow/core:protos_all_py",
+        "//tensorflow/python:array_ops",
+        "//tensorflow/python:auto_control_deps",
+        "//tensorflow/python:constant_op",
+        "//tensorflow/python:dtypes",
+        "//tensorflow/python:errors",
+        "//tensorflow/python:framework_ops",
+        "//tensorflow/python:func_graph",
+        "//tensorflow/python:math_ops",
+        "//tensorflow/python:resource_variable_ops",
+        "//tensorflow/python:tensor_spec",
+        "//tensorflow/python:tensor_util",
+        "//tensorflow/python:util",
+        "//tensorflow/python:variables",
+        "//tensorflow/python/autograph/core",
+        "//tensorflow/python/autograph/impl",
+        "//tensorflow/python/distribute:distribute_lib",
+        "//tensorflow/python/eager:context",
+        "//tensorflow/python/eager:execute",
+        "//tensorflow/python/eager:function",
+        "//tensorflow/python/keras:backend",
+        "//tensorflow/python/keras:constraints",
+        "//tensorflow/python/keras:initializers",
+        "//tensorflow/python/keras:metrics",
+        "//tensorflow/python/keras:regularizers",
+        "//tensorflow/python/keras/engine",
+        "//tensorflow/python/keras/engine:base_layer_utils",
+        "//tensorflow/python/keras/engine:input_spec",
+        "//tensorflow/python/keras/saving",
+        "//tensorflow/python/keras/utils:generic_utils",
+        "//tensorflow/python/keras/utils:layer_utils",
+        "//tensorflow/python/keras/utils:tf_utils",
+        "//tensorflow/python/module",
+        "//tensorflow/python/ops/ragged:ragged_tensor",
+        "//tensorflow/python/training/tracking",
+        "//tensorflow/python/training/tracking:base",
+        "//tensorflow/python/training/tracking:data_structures",
+        "//tensorflow/python/training/tracking:layer_utils",
+        "//tensorflow/tools/docs:doc_controls",
+        "//third_party/py/numpy",
+        "@six_archive//:six",
+    ],
+)
+
+tf_py_test(
+    name = "legacy_base_layer_test",
+    size = "medium",
+    srcs = ["legacy_base_layer_test.py"],
+    python_version = "PY3",
+    shard_count = 8,
+    tags = [
+        "no_rocm",
+        "nomac",  # TODO(mihaimaruseac): b/127695564
+    ],
+    deps = [
+        ":legacy_base_layer",
+        "//tensorflow/python:client_testlib",
+        "//tensorflow/python/keras",
+        "//third_party/py/numpy",
+        "@absl_py//absl/testing:parameterized",
+    ],
+)

tensorflow/tools/pip_package/BUILD

@@ -113,6 +113,7 @@ COMMON_PIP_DEPS = [
     "//tensorflow/python/distribute:combinations",
     "//tensorflow/python/distribute:multi_process_runner",
     "//tensorflow/python/eager:eager_pip",
+    "//tensorflow/python/frozen_keras/engine:legacy_base_layer",
     "//tensorflow/python/keras:combinations",
     "//tensorflow/python/keras/layers/preprocessing:preprocessing_test_utils",
     "//tensorflow/python/keras/distribute:distribute_strategy_test_lib",