[build] Add new flutter_app GN template for Fuchsia style package management (#2999)

build/flx.gni → build/flutter_app.gni

@@ -2,37 +2,60 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-template("flx") {
+assert(is_fuchsia)
+
+import("//build/dart/dart_package.gni")
+
+# Defines a Flutter application
+#
+# Parameters
+#
+#   main_dart (required)
+#     Name of the Dart file containing the main function.
+#
+#   package_name (optional)
+#     Name of the Dart package.
+#
+#   output_name (optional)
+#     Name of output to generate. Defaults to $target_name.flx.
+#
+#   deps (optional)
+#     List of Dart packages the application depends on.
+template("flutter_app") {
+  assert(defined(invoker.main_dart), "Must define main_dart")
+
+  dart_package_name = target_name + "_dart_package"
+
+  dart_package(dart_package_name) {
+    forward_variables_from(invoker, [ "deps" ])
+    if (defined(invoker.package_name)) {
+      package_name = invoker.package_name
+    } else {
+      infer_package_name = true
+    }
+  }
+
   if (defined(invoker.output_name)) {
     bundle_name = invoker.output_name
   } else {
     bundle_name = "${target_name}.flx"
   }
 
+  flutter_snapshot_label = "//flutter/snapshotter($host_toolchain)"
+  flutter_snapshot_dir = get_label_info(flutter_snapshot_label, "root_out_dir")
+  flutter_snapshot = "$flutter_snapshot_dir/sky_snapshot"
+
   bundle_path = "$root_out_dir/$bundle_name"
   snapshot_path = "$target_gen_dir/${target_name}_snapshot.bin"
   depfile_path = "${snapshot_path}.d"
 
   main_dart = invoker.main_dart
 
-  if (defined(invoker.packages)) {
-    packages_path = invoker.packages
-  } else {
-    main_dir = get_path_info(main_dart, "dir")
-    package_dir = get_path_info(main_dir, "dir")
-    packages_path = "$package_dir/.packages"
-  }
-
-  sky_snapshot_label = "//flutter/snapshotter($host_toolchain)"
-  sky_snapshot_dir = get_label_info(sky_snapshot_label, "root_out_dir")
-  sky_snapshot = "$sky_snapshot_dir/sky_snapshot"
-
   action(target_name) {
     depfile = depfile_path
 
     inputs = [
       main_dart,
-      packages_path,
     ]
 
     outputs = [
@@ -47,18 +70,26 @@ template("flx") {
     script = "//flutter/build/package.py"
 
     args = [
-      "--snapshotter", rebase_path(sky_snapshot),
-      "--main-dart", rebase_path(main_dart),
-      "--packages", rebase_path(packages_path),
-      "--bundle", rebase_path(bundle_path),
-      "--bundle-header", "#!mojo mojo:flutter_content_handler",
-      "--snapshot", rebase_path(snapshot_path),
-      "--depfile", rebase_path(depfile_path),
-      "--build-output", rebase_path(bundle_path, root_build_dir),
+      "--snapshotter",
+      rebase_path(flutter_snapshot),
+      "--main-dart",
+      rebase_path(main_dart),
+      "--packages",
+      rebase_path("$target_gen_dir/.packages"),
+      "--bundle",
+      rebase_path(bundle_path),
+      "--bundle-header",
+      "#!mojo mojo:flutter_content_handler",
+      "--snapshot",
+      rebase_path(snapshot_path),
+      "--depfile",
+      rebase_path(depfile_path),
+      "--build-output",
+      rebase_path(bundle_path, root_build_dir),
     ]
 
     deps = [
-      sky_snapshot_label,
+      flutter_snapshot_label,
     ]
 
     if (defined(invoker.deps)) {

examples/spinning_square/BUILD.gn

@@ -2,8 +2,8 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-import("//flutter/build/flx.gni")
+import("//flutter/build/flutter_app.gni")
 
-flx("spinning_square") {
+flutter_app("spinning_square") {
   main_dart = "lib/main.dart"
 }