chore: import upstream snapshot with attribution

tensorflow/compiler/plugin/BUILD

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+# Copyright 2017 The TensorFlow Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ==============================================================================
+
+load("//tensorflow/core/platform:rules_cc.bzl", "cc_library")
+
+"""Configuration file for an XLA plugin.
+
+  please don't check in changes to this file. to prevent changes appearing
+  in git status, use:
+
+  git update-index --assume-unchanged tensorflow/compiler/plugin/BUILD
+
+  To add additional devices to the XLA subsystem, add targets to the
+  dependency list in the 'plugin' target. For instance:
+
+    deps = ["//tensorflow/compiler/plugin/example:plugin_lib"],
+
+  ** Please don't remove this file - it is supporting some 3rd party plugins **
+"""
+
+package(
+    # copybara:uncomment default_applicable_licenses = ["//tensorflow:license"],
+    default_visibility = ["//visibility:public"],
+    licenses = ["notice"],
+)
+
+cc_library(
+    name = "plugin",
+    deps = [
+        #"//tensorflow/compiler/plugin/example:example_lib",
+    ],
+)
+
+# This target is added purely for the purpose of ensuring that `:xla_device` is
+# always publicly visible to external XLA backend/plugin developers.
+cc_library(
+    name = "plugin_device",
+    deps = [
+        "//tensorflow/compiler/jit:xla_device",
+    ],
+)

tensorflow/compiler/plugin/README.md

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+## 3rd party XLA devices
+
+This directory is intended as a place for 3rd party XLA devices which are _not_
+integrated into the public repository.
+
+By adding entries to the BUILD target in this directory, a third party device
+can be included as a dependency of the JIT subsystem.
+
+For integration into the unit test system, see the files:
+
+-   tensorflow/compiler/tests/plugin.bzl
+-   tensorflow/compiler/xla/tests/plugin.bzl