Add ash SessionStateDelegate

ash/wm/stacking_controller.cc

Index: ash/wm/stacking_controller.cc
diff --git a/ash/wm/stacking_controller.cc b/ash/wm/stacking_controller.cc
index bbafab48b6d33324266f2b08e3551ba873ffa07e..3802440be6da86583f1893ddfd66be6879552de9 100644
--- a/ash/wm/stacking_controller.cc
+++ b/ash/wm/stacking_controller.cc
@@ -5,8 +5,8 @@
 #include "ash/wm/stacking_controller.h"
 
 #include "ash/display/display_controller.h"
+#include "ash/session_state_delegate.h"
 #include "ash/shell.h"
-#include "ash/shell_delegate.h"
 #include "ash/shell_window_ids.h"
 #include "ash/wm/always_on_top_controller.h"
 #include "ash/wm/coordinate_conversion.h"
@@ -119,8 +119,9 @@ aura::Window* StackingController::GetSystemModalContainer(
 
   // If screen lock is not active and user session is active,
   // all modal windows are placed into the normal modal container.
-  if (!Shell::GetInstance()->delegate()->IsScreenLocked() &&
-      Shell::GetInstance()->delegate()->IsSessionStarted()) {
+  if (!Shell::GetInstance()->session_state_delegate()->IsScreenLocked() &&
+      Shell::GetInstance()->session_state_delegate()->
+          IsActiveUserSessionStarted()) {
     return GetContainerById(root,
                             internal::kShellWindowId_SystemModalContainer);
   }