Rationalize Dart mojo and sky package structure

services/dart/dart_app.cc

Index: services/dart/dart_app.cc
diff --git a/services/dart/dart_app.cc b/services/dart/dart_app.cc
index 02b66bd1b447b961628fa5b95871e0113de0ac1d..a2ae23f49c48dd7e5ea47c77a3031aa7390b9265 100644
--- a/services/dart/dart_app.cc
+++ b/services/dart/dart_app.cc
@@ -29,9 +29,11 @@ DartApp::DartApp(mojo::InterfaceRequest<Application> application_request,
 
   CHECK(unpacked_app_directory_.CreateUniqueTempDir());
   ExtractApplication(response.Pass());
-  base::FilePath package_root = unpacked_app_directory_.path();
+  base::FilePath package_root =
+      unpacked_app_directory_.path().AppendASCII("packages");
 
-  base::FilePath entry_path = package_root.Append("main.dart");
+  base::FilePath entry_path =
+      unpacked_app_directory_.path().Append("main.dart");
   std::string source;
   if (!base::ReadFileToString(entry_path, &source)) {
     NOTREACHED();