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

build/android/dex_action.gypi

+# Copyright 2013 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 provide a rule that dexes
+# compiled java files. If proguard_enabled == "true" and CONFIGURATION_NAME ==
+# "Release", then it will dex the proguard_enabled_input_path instead of the
+# normal dex_input_paths/dex_generated_input_paths.
+#
+# To use this, create a gyp target with the following form:
+#  {
+#    'action_name': 'some name for the action'
+#    'actions': [
+#      'variables': {
+#        'dex_input_paths': [ 'files to dex (when proguard is not used) and add to input paths' ],
+#        'dex_generated_input_dirs': [ 'dirs that contain generated files to dex' ],
+#
+#        # For targets that use proguard:
+#        'proguard_enabled': 'true',
+#        'proguard_enabled_input_path': 'path to dex when using proguard',
+#      },
+#      'includes': [ 'relative/path/to/dex_action.gypi' ],
+#    ],
+#  },
+#
+
+{
+  'message': 'Creating dex file: <(output_path)',
+  'variables': {
+    'dex_input_paths': [],
+    'dex_generated_input_dirs': [],
+    'proguard_enabled%': 'false',
+    'proguard_enabled_input_path%': '',
+    'dex_no_locals%': 0,
+    'dex_additional_options': [],
+  },
+  'inputs': [
+    '<(DEPTH)/build/android/gyp/util/build_utils.py',
+    '<(DEPTH)/build/android/gyp/util/md5_check.py',
+    '<(DEPTH)/build/android/gyp/dex.py',
+    '>@(dex_input_paths)',
+  ],
+  'outputs': [
+    '<(output_path)',
+    '<(output_path).inputs',
+  ],
+  'action': [
+    'python', '<(DEPTH)/build/android/gyp/dex.py',
+    '--dex-path=<(output_path)',
+    '--android-sdk-tools=<(android_sdk_tools)',
+    '--output-directory=<(PRODUCT_DIR)',
+    '--configuration-name=<(CONFIGURATION_NAME)',
+    '--proguard-enabled=>(proguard_enabled)',
+    '--proguard-enabled-input-path=<(proguard_enabled_input_path)',
+    '--no-locals=>(dex_no_locals)',
+    '>@(dex_additional_options)',
+    '>@(dex_input_paths)',
+    '>@(dex_generated_input_dirs)',
+  ]
+}