mash: Convert all of //ash/system to use WmShelf

ash/focus_cycler_unittest.cc

Index: ash/focus_cycler_unittest.cc
diff --git a/ash/focus_cycler_unittest.cc b/ash/focus_cycler_unittest.cc
index 664a32f020953aca75f1f3e0af2cdb1a9c4082ad..b7b75bece5de90c7e06068335097e67113dd80ba 100644
--- a/ash/focus_cycler_unittest.cc
+++ b/ash/focus_cycler_unittest.cc
@@ -6,6 +6,7 @@
 
 #include <memory>
 
+#include "ash/common/shelf/wm_shelf.h"
 #include "ash/common/shell_window_ids.h"
 #include "ash/common/wm_shell.h"
 #include "ash/common/wm_window.h"
@@ -96,7 +97,8 @@ class FocusCyclerTest : public AshTestBase {
         WmShell::Get()->GetRootWindowForNewWindows()->GetChildByShellWindowId(
             kShellWindowId_StatusContainer);
 
-    StatusAreaWidget* widget = new StatusAreaWidget(parent, GetPrimaryShelf());
+    StatusAreaWidget* widget =
+        new StatusAreaWidget(parent, WmShelf::ForPrimaryDisplay());
     widget->CreateTrayViews();
     widget->Show();
     tray_.reset(widget->system_tray());