Promotes more accessors from WmShell to Shell

ash/common/system/chromeos/bluetooth/tray_bluetooth.cc

Index: ash/common/system/chromeos/bluetooth/tray_bluetooth.cc
diff --git a/ash/common/system/chromeos/bluetooth/tray_bluetooth.cc b/ash/common/system/chromeos/bluetooth/tray_bluetooth.cc
index 436c19499592a799eacbc587d78f031590cedba4..3b6e75e490ce6eaecdafb6e28ad19979a3bd7931 100644
--- a/ash/common/system/chromeos/bluetooth/tray_bluetooth.cc
+++ b/ash/common/system/chromeos/bluetooth/tray_bluetooth.cc
@@ -597,11 +597,11 @@ TrayBluetooth::TrayBluetooth(SystemTray* system_tray)
     : SystemTrayItem(system_tray, UMA_BLUETOOTH),
       default_(nullptr),
       detailed_(nullptr) {
-  WmShell::Get()->system_tray_notifier()->AddBluetoothObserver(this);
+  Shell::Get()->system_tray_notifier()->AddBluetoothObserver(this);
 }
 
 TrayBluetooth::~TrayBluetooth() {
-  WmShell::Get()->system_tray_notifier()->RemoveBluetoothObserver(this);
+  Shell::Get()->system_tray_notifier()->RemoveBluetoothObserver(this);
 }
 
 views::View* TrayBluetooth::CreateTrayView(LoginStatus status) {