Centralizes more shared code between ash and mash

ash/wm/always_on_top_controller_unittest.cc

Index: ash/wm/always_on_top_controller_unittest.cc
diff --git a/ash/wm/always_on_top_controller_unittest.cc b/ash/wm/always_on_top_controller_unittest.cc
index 61c21d2565b36b0035174350588aab3f0ff34d9c..76686ccf36253abdb62ee32bbf7dcf203e6009ce 100644
--- a/ash/wm/always_on_top_controller_unittest.cc
+++ b/ash/wm/always_on_top_controller_unittest.cc
@@ -4,6 +4,7 @@
 
 #include "ash/common/wm/always_on_top_controller.h"
 
+#include "ash/aura/wm_root_window_controller_aura.h"
 #include "ash/aura/wm_window_aura.h"
 #include "ash/common/shell_window_ids.h"
 #include "ash/common/wm/workspace/workspace_layout_manager.h"
@@ -67,7 +68,7 @@ TEST_F(VirtualKeyboardAlwaysOnTopControllerTest, NotifyKeyboardBoundsChanged) {
       new TestLayoutManager(WmWindowAura::Get(always_on_top_container));
   RootWindowController* controller = Shell::GetPrimaryRootWindowController();
   AlwaysOnTopController* always_on_top_controller =
-      controller->always_on_top_controller();
+      controller->wm_root_window_controller()->always_on_top_controller();
   always_on_top_controller->SetLayoutManagerForTest(base::WrapUnique(manager));
   // Activate keyboard. This triggers keyboard listeners to be registered.
   controller->ActivateKeyboard(keyboard_controller);