Remove app_shell chrome.shell API and ShellAppWindow

athena/content/chrome/content_activity_factory.cc

Index: athena/content/chrome/content_activity_factory.cc
diff --git a/athena/content/chrome/content_activity_factory.cc b/athena/content/chrome/content_activity_factory.cc
index a8ba6d5a1e099e195193cf9123d74cbf4177b171..f3c9592ce07991dda9adadd105b3211f656ce179 100644
--- a/athena/content/chrome/content_activity_factory.cc
+++ b/athena/content/chrome/content_activity_factory.cc
@@ -53,10 +53,4 @@ Activity* ContentActivityFactory::CreateAppActivity(
   return new ChromeAppActivity(app_window, web_view);
 }
 
-Activity* ContentActivityFactory::CreateAppActivity(
-    extensions::ShellAppWindow* app_window,
-    const std::string& app_id) {
-  return NULL;
-}
-
 }  // namespace athena