Add a snapshot of flutter/engine/src/build to our sdk

build/copy_test_data_ios.gypi

Index: build/copy_test_data_ios.gypi
diff --git a/build/copy_test_data_ios.gypi b/build/copy_test_data_ios.gypi
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+# Copyright (c) 2012 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.
+
+# This file is meant to be included into an action to copy test data files into
+# an iOS app bundle. To use this the following variables need to be defined:
+#   test_data_files: list: paths to test data files or directories
+#   test_data_prefix: string: a directory prefix that will be prepended to each
+#                             output path.  Generally, this should be the base
+#                             directory of the gypi file containing the unittest
+#                             target (e.g. "base" or "chrome").
+#
+# To use this, create a gyp target with the following form:
+# {
+#   'target_name': 'my_unittests',
+#   'conditions': [
+#     ['OS == "ios"', {
+#       'actions': [
+#         {
+#           'action_name': 'copy_test_data',
+#           'variables': {
+#             'test_data_files': [
+#               'path/to/datafile.txt',
+#               'path/to/data/directory/',
+#             ]
+#             'test_data_prefix' : 'prefix',
+#           },
+#           'includes': ['path/to/this/gypi/file'],
+#         },
+#       ],
+#     }],
+# }
+#
+
+{
+  'inputs': [
+    # The |-o <(test_data_prefix)| is ignored; it is there to work around a
+    # caching bug in gyp (https://code.google.com/p/gyp/issues/detail?id=112).
+    # It caches command output when the string is the same, so if two copy
+    # steps have the same relative paths, there can be bogus cache hits that
+    # cause compile failures unless something varies.
+    '<!@pymod_do_main(copy_test_data_ios -o <(test_data_prefix) --inputs <(test_data_files))',
+  ],
+  'outputs': [
+    '<!@pymod_do_main(copy_test_data_ios -o <(PRODUCT_DIR)/<(_target_name).app/<(test_data_prefix) --outputs <(test_data_files))',
+  ],
+  'action': [
+    'python',
+    '<(DEPTH)/build/copy_test_data_ios.py',
+    '-o', '<(PRODUCT_DIR)/<(_target_name).app/<(test_data_prefix)',
+    '<@(_inputs)',
+  ],
+}