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

build/jni_generator.gypi

+# 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 a target to provide a rule
+# to generate jni bindings for Java-files in a consistent manner.
+#
+# To use this, create a gyp target with the following form:
+#  {
+#    'target_name': 'base_jni_headers',
+#    'type': 'none',
+#    'sources': [
+#      'android/java/src/org/chromium/base/BuildInfo.java',
+#      ...
+#      ...
+#      'android/java/src/org/chromium/base/SystemMessageHandler.java',
+#    ],
+#    'variables': {
+#      'jni_gen_package': 'base',
+#    },
+#    'includes': [ '../build/jni_generator.gypi' ],
+#  },
+#
+# The generated file name pattern can be seen on the "outputs" section below.
+# (note that RULE_INPUT_ROOT is the basename for the java file).
+#
+# See base/android/jni_generator/jni_generator.py for more info about the
+# format of generating JNI bindings.
+
+{
+  'variables': {
+    'jni_generator': '<(DEPTH)/base/android/jni_generator/jni_generator.py',
+    'jni_generator_jarjar_file%': '',
+    'jni_generator_ptr_type%': 'long',
+    # A comma separated string of include files.
+    'jni_generator_includes%': (
+        'base/android/jni_generator/jni_generator_helper.h'
+    ),
+    'native_exports%': '--native_exports_optional',
+  },
+  'rules': [
+    {
+      'rule_name': 'generate_jni_headers',
+      'extension': 'java',
+      'inputs': [
+        '<(jni_generator)',
+      ],
+      'outputs': [
+        '<(SHARED_INTERMEDIATE_DIR)/<(jni_gen_package)/jni/<(RULE_INPUT_ROOT)_jni.h',
+      ],
+      'action': [
+        '<(jni_generator)',
+        '--input_file',
+        '<(RULE_INPUT_PATH)',
+        '--output_dir',
+        '<(SHARED_INTERMEDIATE_DIR)/<(jni_gen_package)/jni',
+        '--includes',
+        '<(jni_generator_includes)',
+        '--optimize_generation',
+        '<(optimize_jni_generation)',
+        '--jarjar',
+        '<(jni_generator_jarjar_file)',
+        '--ptr_type',
+        '<(jni_generator_ptr_type)',
+        '<(native_exports)',
+      ],
+      'message': 'Generating JNI bindings from <(RULE_INPUT_PATH)',
+      'process_outputs_as_sources': 1,
+      'conditions': [
+        ['jni_generator_jarjar_file != ""', {
+          'inputs': [
+            '<(jni_generator_jarjar_file)',
+          ],
+        }]
+      ],
+    },
+  ],
+  'direct_dependent_settings': {
+    'include_dirs': [
+      '<(SHARED_INTERMEDIATE_DIR)/<(jni_gen_package)',
+    ],
+  },
+  # This target exports a hard dependency because it generates header
+  # files.
+  'hard_dependency': 1,
+}
+