Promotes more accessors from WmShell to Shell

ash/common/system/chromeos/screen_security/screen_capture_tray_item.cc

Index: ash/common/system/chromeos/screen_security/screen_capture_tray_item.cc
diff --git a/ash/common/system/chromeos/screen_security/screen_capture_tray_item.cc b/ash/common/system/chromeos/screen_security/screen_capture_tray_item.cc
index daa53f7f4c38c89430c17365b828269e2998f9b1..3920c4ed76a7e24e28771ab8df0e9edcdfdcfff2 100644
--- a/ash/common/system/chromeos/screen_security/screen_capture_tray_item.cc
+++ b/ash/common/system/chromeos/screen_security/screen_capture_tray_item.cc
@@ -30,12 +30,12 @@ const char kScreenCaptureNotificationId[] = "chrome://screen/capture";
 ScreenCaptureTrayItem::ScreenCaptureTrayItem(SystemTray* system_tray)
     : ScreenTrayItem(system_tray, UMA_SCREEN_CAPTURE) {
   Shell::GetInstance()->AddShellObserver(this);
-  WmShell::Get()->system_tray_notifier()->AddScreenCaptureObserver(this);
+  Shell::Get()->system_tray_notifier()->AddScreenCaptureObserver(this);
 }
 
 ScreenCaptureTrayItem::~ScreenCaptureTrayItem() {
   Shell::GetInstance()->RemoveShellObserver(this);
-  WmShell::Get()->system_tray_notifier()->RemoveScreenCaptureObserver(this);
+  Shell::Get()->system_tray_notifier()->RemoveScreenCaptureObserver(this);
 }
 
 views::View* ScreenCaptureTrayItem::CreateDefaultView(LoginStatus status) {