Linux create_sdk GN build for host

utils/invoke_dart.gni

+# Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
+# for details. All rights reserved. Use of this source code is governed by a
+# BSD-style license that can be found in the LICENSE file.
+
+template("invoke_dart") {
+  assert(defined(invoker.outputs), "invoke_dart must specify outputs")
+  assert(defined(invoker.dart_root), "Where is the dart root?")
+  dart_root = invoker.dart_root

[Cutch, 2016/09/29 16:41:26]

can't we automatically detect the dart root from the path of this gni file? Use
rebase path to get the absolute path of this file and then it's just ../ from
there.

[zra, 2016/09/29 17:46:41]

Done.

+  extra_deps = []
+  if (defined(invoker.deps)) {
+    extra_deps += invoker.deps
+  }
+
+  extra_inputs = []
+  if (defined(invoker.inputs)) {
+    extra_inputs += invoker.inputs
+  }
+
+  extra_args = []
+  if (defined(invoker.args)) {
+    extra_args += invoker.args
+  }
+
+  action(target_name) {
+    deps = extra_deps + [
+      "$dart_root/runtime/bin:dart($host_toolchain)",
+    ]
+
+    dart_out_dir = get_label_info(
+        "$dart_root/runtime/bin:dart($host_toolchain)", "root_out_dir")
+    # TODO(zra): Add platform specific executable suffix (e.g. .exe on win)
+    dart = rebase_path("$dart_out_dir/dart")
+
+    inputs = [
+      dart,
+    ] + extra_inputs
+
+    outputs = invoker.outputs
+
+    script = "$dart_root/tools/dart_for_gn.py"
+    args = [
+      dart,
+    ] + extra_args
+  }
+}
+
+template("application_snapshot") {
+  assert(defined(invoker.dart_root), "Must specify 'dart_root'")
+  assert(defined(invoker.main_dart), "Must specify 'main_dart'")
+  main_dart = invoker.main_dart
+  name = target_name
+  if (defined(invoker.name)) {
+    name = invoker.name
+  }
+  extra_deps = []
+  if (defined(invoker.deps)) {
+    extra_deps += invoker.deps
+  }
+  extra_inputs = []
+  if (defined(invoker.inputs)) {
+    extra_inputs += invoker.inputs
+  }
+  invoke_dart(target_name) {
+    dart_root = invoker.dart_root
+    deps = extra_deps + [
+      "$dart_root/pkg:pkg_files_stamp"
+    ]
+
+    inputs = extra_inputs + [
+      "$dart_root/sdk/lib/_internal/sdk_library_metadata/lib/libraries.dart",
+      "$root_gen_dir/pkg_files.stamp",
+    ]
+
+    output = "$root_gen_dir/$name.dart.snapshot"
+    outputs = [
+      output,
+    ]
+
+    dot_packages = rebase_path("$dart_root/.packages")
+    abs_output = rebase_path(output)
+    main_file = rebase_path(main_dart)
+
+    args = [
+      "--packages=$dot_packages",
+      "--snapshot=$abs_output",
+      main_file
+    ]
+  }
+}