Promotes more accessors from WmShell to Shell

ash/system/chromeos/power/power_event_observer.cc

Index: ash/system/chromeos/power/power_event_observer.cc
diff --git a/ash/system/chromeos/power/power_event_observer.cc b/ash/system/chromeos/power/power_event_observer.cc
index 88454e0ad2030698b41045b05e3e49cdb4f3ac55..b18e340f92434a04dec5350b6f24e08c332022b4 100644
--- a/ash/system/chromeos/power/power_event_observer.cc
+++ b/ash/system/chromeos/power/power_event_observer.cc
@@ -134,7 +134,7 @@ void PowerEventObserver::SuspendDone(const base::TimeDelta& sleep_duration) {
   // here: http://crbug.com/692193
   if (!WmShell::Get()->IsRunningInMash())
     Shell::GetInstance()->display_configurator()->ResumeDisplays();
-  WmShell::Get()->system_tray_notifier()->NotifyRefreshClock();
+  Shell::Get()->system_tray_notifier()->NotifyRefreshClock();
 
   // If the suspend request was being blocked while waiting for the lock
   // animation to complete, clear the blocker since the suspend has already