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

build/android/finalize_apk_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 an action that
+# signs and zipaligns an APK.
+#
+# To use this, create a gyp action with the following form:
+#  {
+#    'action_name': 'some descriptive action name',
+#    'variables': {
+#      'input_apk_path': 'relative/path/to/input.apk',
+#      'output_apk_path': 'relative/path/to/output.apk',
+#    },
+#    'includes': [ '../../build/android/finalize_apk_action.gypi' ],
+#  },
+#
+
+{
+  'message': 'Signing/aligning <(_target_name) APK: <(input_apk_path)',
+  'variables': {
+    'keystore_path%': '<(DEPTH)/build/android/ant/chromium-debug.keystore',
+    'keystore_name%': 'chromiumdebugkey',
+    'keystore_password%': 'chromium',
+    'zipalign_path%': '<(android_sdk_tools)/zipalign',
+    'rezip_apk_jar_path%': '<(PRODUCT_DIR)/lib.java/rezip_apk.jar',
+    'load_library_from_zip%': 0,
+  },
+  'inputs': [
+    '<(DEPTH)/build/android/gyp/finalize_apk.py',
+    '<(DEPTH)/build/android/gyp/util/build_utils.py',
+    '<(keystore_path)',
+    '<(input_apk_path)',
+  ],
+  'outputs': [
+    '<(output_apk_path)',
+  ],
+  'action': [
+    'python', '<(DEPTH)/build/android/gyp/finalize_apk.py',
+    '--zipalign-path=<(zipalign_path)',
+    '--unsigned-apk-path=<(input_apk_path)',
+    '--final-apk-path=<(output_apk_path)',
+    '--key-path=<(keystore_path)',
+    '--key-name=<(keystore_name)',
+    '--key-passwd=<(keystore_password)',
+    '--load-library-from-zip=<(load_library_from_zip)',
+    '--rezip-apk-jar-path=<(rezip_apk_jar_path)',
+  ],
+}