Promotes more accessors from WmShell to Shell

ash/common/system/tray/system_tray_controller.cc

Index: ash/common/system/tray/system_tray_controller.cc
diff --git a/ash/common/system/tray/system_tray_controller.cc b/ash/common/system/tray/system_tray_controller.cc
index 547ac9943c3ae7afb074562f54913e3331af1f4c..756c7e8bc1a30291cbb48a2a59fe2d76191b41da 100644
--- a/ash/common/system/tray/system_tray_controller.cc
+++ b/ash/common/system/tray/system_tray_controller.cc
@@ -10,6 +10,7 @@
 #include "ash/common/wm_shell.h"
 #include "ash/common/wm_window.h"
 #include "ash/root_window_controller.h"
+#include "ash/shell.h"
 
 namespace ash {
 
@@ -179,7 +180,7 @@ void SystemTrayController::SetPrimaryTrayVisible(bool visible) {
 
 void SystemTrayController::SetUse24HourClock(bool use_24_hour) {
   hour_clock_type_ = use_24_hour ? base::k24HourClock : base::k12HourClock;
-  WmShell::Get()->system_tray_notifier()->NotifyDateFormatChanged();
+  Shell::Get()->system_tray_notifier()->NotifyDateFormatChanged();
 }
 
 void SystemTrayController::ShowUpdateIcon(mojom::UpdateSeverity severity,