Add Python util to read from a data pipe into a bytearray

mojo/python/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//mojo/public/python/rules.gni")
 import("//third_party/cython/rules.gni")
 
 # GYP version: mojo/mojo.gyp:mojo_python
 group("python") {
   deps = [
     ":mojo_embedder",
+    ":packaged_utils",
+    ":utils",
     ":validation_util",
     "//mojo/public/python",
   ]
 }
 
+copy("utils") {
+  sources = [
+    "mojo_utils/__init__.py",
+    "mojo_utils/data_pipe_utils.py",
+  ]
+  outputs = [
+    "$root_out_dir/python/mojo_utils/{{source_file_part}}",
+  ]
+}
+
+python_package("packaged_utils") {
+  sources = [
+    "mojo_utils/__init__.py",
+    "mojo_utils/data_pipe_utils.py",
+  ]
+  datadeps = [
+    "//mojo/public/python:mojo_system",
+  ]
+}
+
 # GYP version: mojo/mojo.gyp:mojo_python_embedder
 python_binary_module("mojo_embedder") {
   cython_sources = [ "system/mojo_embedder.pyx" ]
   deps = [
     "//mojo/edk/system",
   ]
   datadeps = [
     "//mojo/public/python:mojo_system",
   ]
 }
@@ skipping 10 matching lines @@
 python_binary_module("validation_util") {
   python_base_module = "mojo_tests"
   cython_sources = [ "system/mojo_tests/validation_util.pyx" ]
   deps = [
     "//mojo/public/cpp/bindings/tests:mojo_public_bindings_test_utils",
   ]
   datadeps = [
     ":tests_module",
   ]
 }