Introduce Sky packaged apps.

sky/examples/hello_world/BUILD.gn

Index: sky/examples/hello_world/BUILD.gn
diff --git a/sky/examples/hello_world/BUILD.gn b/sky/examples/hello_world/BUILD.gn
new file mode 100644
index 0000000000000000000000000000000000000000..3b6e4f2c3894ea8f8289d16365bb0ff9d21b671c
--- /dev/null
+++ b/sky/examples/hello_world/BUILD.gn
@@ -0,0 +1,12 @@
+# Copyright 2015 The Chromium Authors. All rights reserved.
+
+import("//mojo/public/dart/rules.gni")
+
+dart_packaged_application("sky_hello_world") {

[tonyg, 2015/04/14 14:36:56]

This is kind of a bikeshed, but I'm wondering whether this'd make more sense as
sky_packaged_application (which is basically an alias for uses_pub and
uses_sky).

[hansmuller1, 2015/04/14 15:02:40]

I agree!

+  sources = [
+    "hello_world.dart",
+    "main.sky",
+  ]
+  uses_sky = true
+  uses_pub = true
+}