Separate athena's startup process from AppShell's

athena/main/athena_launcher.h

Index: athena/main/athena_launcher.h
diff --git a/athena/main/athena_launcher.h b/athena/main/athena_launcher.h
index c256e7d6a58f607889c4150176e56a5e07c3ee66..cf08dc7f0f2545658b4a484fff50d7d2966a16bf 100644
--- a/athena/main/athena_launcher.h
+++ b/athena/main/athena_launcher.h
@@ -22,12 +22,9 @@ class BrowserContext;
 namespace athena {
 class ActivityFactory;
 class AppModelBuilder;
-class ScreenManagerDelegate;
 
 // Starts down the athena shell environment.
-void StartAthenaEnv(aura::Window* root_window,
-                    ScreenManagerDelegate* screen_manager_delegate,
-                    scoped_refptr<base::TaskRunner> file_runner);
+void StartAthenaEnv(scoped_refptr<base::TaskRunner> file_runner);
 
 void StartAthenaSessionWithContext(content::BrowserContext* context);