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

shell/external_application_listener_unittest.cc

Index: shell/external_application_listener_unittest.cc
diff --git a/shell/external_application_listener_unittest.cc b/shell/external_application_listener_unittest.cc
index ff381b34994c2facce548a5e6d96966d4f27a819..9bee93ca7eedbd6c674707e6c5d668badd993ca2 100644
--- a/shell/external_application_listener_unittest.cc
+++ b/shell/external_application_listener_unittest.cc
@@ -81,7 +81,7 @@ class StubShellImpl : public Shell {
       : application_(application.Pass()), binding_(this) {
     ShellPtr shell;
     binding_.Bind(GetProxy(&shell));
-    application_->Initialize(shell.Pass(), Array<String>());
+    application_->Initialize(shell.Pass(), "", Array<String>());
   }
   ~StubShellImpl() override {}