Separate athena's startup process from AppShell's

athena/home/home_card_impl.cc

Index: athena/home/home_card_impl.cc
diff --git a/athena/home/home_card_impl.cc b/athena/home/home_card_impl.cc
index 042ff6ce971ff71b88eb52496f256b028e4b6671..17ecfc4203e670f6a67c60e97042409f3f16fa3b 100644
--- a/athena/home/home_card_impl.cc
+++ b/athena/home/home_card_impl.cc
@@ -8,6 +8,7 @@
 #include <limits>
 
 #include "athena/common/container_priorities.h"
+#include "athena/env/public/athena_env.h"
 #include "athena/home/app_list_view_delegate.h"
 #include "athena/home/athena_start_page_view.h"
 #include "athena/home/minimized_home.h"
@@ -528,7 +529,7 @@ void HomeCardImpl::Init() {
   int work_area_bottom_inset =
       GetBoundsForState(GetNativeWindow()->bounds(),
                         HomeCard::VISIBLE_MINIMIZED).height();
-  ScreenManager::Get()->SetWorkAreaInsets(
+  AthenaEnv::Get()->SetDisplayWorkAreaInsets(
       gfx::Insets(0, 0, work_area_bottom_inset, 0));
 }