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

sky/viewer/content_handler_impl.cc

Index: sky/viewer/content_handler_impl.cc
diff --git a/sky/viewer/content_handler_impl.cc b/sky/viewer/content_handler_impl.cc
index 4e70167fa477e8599dfee22eb52447cd5114f470..ffdcdb0532e738129af83a5ba5870bd1a1c4c8c6 100644
--- a/sky/viewer/content_handler_impl.cc
+++ b/sky/viewer/content_handler_impl.cc
@@ -22,6 +22,7 @@ class SkyApplication : public mojo::Application {
         initial_response_(response.Pass()) {}
 
   void Initialize(mojo::ShellPtr shell,
+                  const mojo::String& url,
                   mojo::Array<mojo::String> args) override {
     shell_ = shell.Pass();
     mojo::ServiceProviderPtr service_provider;