Pass the final URL an app was loaded from to the app in Initialize().

examples/python/__mojo__.py

Index: examples/python/__mojo__.py
diff --git a/examples/python/__mojo__.py b/examples/python/__mojo__.py
index 03ec960aa7fc2dc2f41ec34f679b6299262e2fa9..ce13efb457cd945ff5419a1bb8537ffc029374b1 100644
--- a/examples/python/__mojo__.py
+++ b/examples/python/__mojo__.py
@@ -18,7 +18,7 @@ class ApplicationImpl(application_mojom.Application):
     self._providers = []
     application_mojom.Application.manager.Bind(self, app_request_handle)
 
-  def Initialize(self, shell, args):
+  def Initialize(self, shell, url, args):
     self.shell = shell
 
   def AcceptConnection(self, requestor_url, services, exposed_services):