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

build/android/apkbuilder_action.gypi

+# Copyright 2015 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 a helper to java_apk.gypi. It should be used to create an
+# action that runs ApkBuilder via ANT.
+#
+# Required variables:
+#  apk_name - File name (minus path & extension) of the output apk.
+#  apk_path - Path to output apk.
+#  package_input_paths - Late-evaluated list of resource zips.
+#  native_libs_dir - Path to lib/ directory to use. Set to an empty directory
+#    if no native libs are needed.
+# Optional variables:
+#  has_code - Whether to include classes.dex in the apk.
+#  dex_path - Path to classes.dex. Used only when has_code=1.
+#  extra_inputs - List of extra action inputs.
+{
+  'variables': {
+    'variables': {
+      'has_code%': 1,
+    },
+    'conditions': [
+      ['has_code == 0', {
+        'has_code_str': 'false',
+      }, {
+        'has_code_str': 'true',
+      }],
+    ],
+    'has_code%': '<(has_code)',
+    'extra_inputs%': [],
+    # Write the inputs list to a file, so that its mtime is updated when
+    # the list of inputs changes.
+    'inputs_list_file': '>|(apk_package.<(_target_name).<(apk_name).gypcmd >@(package_input_paths))',
+    'resource_packaged_apk_name': '<(apk_name)-resources.ap_',
+    'resource_packaged_apk_path': '<(intermediate_dir)/<(resource_packaged_apk_name)',
+  },
+  'action_name': 'apkbuilder_<(apk_name)',
+  'message': 'Packaging <(apk_name)',
+  'inputs': [
+    '<(DEPTH)/build/android/ant/apk-package.xml',
+    '<(DEPTH)/build/android/gyp/util/build_utils.py',
+    '<(DEPTH)/build/android/gyp/ant.py',
+    '<(resource_packaged_apk_path)',
+    '<@(extra_inputs)',
+    '>@(package_input_paths)',
+    '>(inputs_list_file)',
+  ],
+  'outputs': [
+    '<(apk_path)',
+  ],
+  'conditions': [
+    ['has_code == 1', {
+      'inputs': ['<(dex_path)'],
+      'action': [
+        '-DDEX_FILE_PATH=<(dex_path)',
+      ]
+    }],
+  ],
+  'action': [
+    'python', '<(DEPTH)/build/android/gyp/ant.py',
+    '--',
+    '-quiet',
+    '-DHAS_CODE=<(has_code_str)',
+    '-DANDROID_SDK_ROOT=<(android_sdk_root)',
+    '-DANDROID_SDK_TOOLS=<(android_sdk_tools)',
+    '-DRESOURCE_PACKAGED_APK_NAME=<(resource_packaged_apk_name)',
+    '-DNATIVE_LIBS_DIR=<(native_libs_dir)',
+    '-DAPK_NAME=<(apk_name)',
+    '-DCONFIGURATION_NAME=<(CONFIGURATION_NAME)',
+    '-DOUT_DIR=<(intermediate_dir)',
+    '-DUNSIGNED_APK_PATH=<(apk_path)',
+    '-DEMMA_INSTRUMENT=<(emma_instrument)',
+    '-DEMMA_DEVICE_JAR=<(emma_device_jar)',
+    '-Dbasedir=.',
+    '-buildfile',
+    '<(DEPTH)/build/android/ant/apk-package.xml',
+  ]
+}