Start including sdk_ext sources in sky dart-pkg

mojo/public/dart/rules.gni

 # 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.
 
 # Rules to generate zipped applications for Dart.
 # Rules to generate dart-pkg and dart-pkg/packages.
 
 import("//build/module_args/mojo.gni")
 
 template("dartzip_package") {
@@ skipping 202 matching lines @@
 # sources. Also copies any mojom dependencies into lib/mojom.
 #
 #   sources
 #       List of sources to include in the package.
 #
 #   deps (optional)
 #       Note: this can only contain mojom targets.
 #
 #   datadeps (optional)
 #
+#   sdk_ext_directory (optional)
+#       Directory containing sdk-ext .dart sources.
+#
 template("dart_pkg") {
   pubspec_yaml_path = rebase_path("pubspec.yaml")
   dart_package_name_script =
       rebase_path("mojo/public/tools/dart_package_name.py", ".", mojo_sdk_root)
   package_name = exec_script(dart_package_name_script,
                              [
                                "--pubspec",
                                pubspec_yaml_path,
                              ],
                              "trim string",
@@ skipping 23 matching lines @@
       root_prefix = rebase_path(".", "", mojo_sdk_root)
       source_directory = rebase_path(get_label_info(d, "dir"))
       mojom_sources += exec_script(list_mojoms_script,
                                    [
                                      source_directory,
                                      root_prefix,
                                    ],
                                    "list lines")
     }
 
+    sdk_ext_directory = []
+    if (defined(invoker.sdk_ext_directory)) {
+      sdk_ext_directory += [ invoker.sdk_ext_directory ]
+    }
+
     script = rebase_path("mojo/public/tools/dart_pkg.py", ".", mojo_sdk_root)
     outputs = [
       stamp_file,
     ]
 
     inputs = [
                list_mojoms_script,
                script,
-             ] + rebase_path(invoker.sources)
+             ] + rebase_path(invoker.sources) + rebase_path(sdk_ext_directory)
 
     args = [
              "--package-name",
              package_name,
              "--gen-directory",
              rebase_path("$root_gen_dir/dart-gen"),
              "--pkg-directory",
              pkg_directory,
              "--package-root",
              package_root,
              "--stamp-file",
              rebase_path(stamp_file),
              "--package-sources",
            ] + rebase_path(invoker.sources) + [ "--mojom-sources" ] +
-           rebase_path(mojom_sources, "", mojo_sdk_root)
+           rebase_path(mojom_sources, "", mojo_sdk_root) +
+           [ "--sdk-ext-directories" ] + rebase_path(sdk_ext_directory)
   }
 }