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

build/util/BUILD.gn

+# Copyright (c) 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.
+
+action("webkit_version") {
+  script = "version.py"
+
+  lastchange_file = "LASTCHANGE.blink"
+
+  # TODO(brettw) move from content to this directory.
+  template_file = "//content/webkit_version.h.in"
+  inputs = [
+    lastchange_file,
+    template_file,
+  ]
+
+  output_file = "$root_gen_dir/webkit_version.h"
+  outputs = [
+    output_file,
+  ]
+
+  args = [
+    "-f",
+    rebase_path(lastchange_file, root_build_dir),
+    rebase_path(template_file, root_build_dir),
+    rebase_path(output_file, root_build_dir),
+  ]
+}
+
+action("chrome_version_json") {
+  script = "version.py"
+  _chrome_version_path = "//chrome/VERSION"
+  inputs = [
+    _chrome_version_path,
+  ]
+  _output_file = "$root_gen_dir/CHROME_VERSION.json"
+  outputs = [
+    _output_file,
+  ]
+  args = [
+    "--file",
+    rebase_path(_chrome_version_path, root_build_dir),
+    "--template",
+    "{\"full-quoted\": \"\\\"@MAJOR@.@MINOR@.@BUILD@.@PATCH@\\\"\"}",
+    "--output",
+    rebase_path(_output_file, root_build_dir),
+  ]
+}