Add the supporting code for the cast system tray integration

ash/system/tray/system_tray_notifier.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/system/tray/system_tray_notifier.h"
 
 namespace ash {
 
 SystemTrayNotifier::SystemTrayNotifier() {
 }
@@ skipping 20 matching lines @@
 }
 
 void SystemTrayNotifier::AddBluetoothObserver(BluetoothObserver* observer) {
   bluetooth_observers_.AddObserver(observer);
 }
 
 void SystemTrayNotifier::RemoveBluetoothObserver(BluetoothObserver* observer) {
   bluetooth_observers_.RemoveObserver(observer);
 }
 
+void SystemTrayNotifier::AddCastObserver(CastObserver* observer) {
+  cast_observers_.AddObserver(observer);
+}
+
+void SystemTrayNotifier::RemoveCastObserver(CastObserver* observer) {
+  cast_observers_.RemoveObserver(observer);
+}
+
 void SystemTrayNotifier::AddClockObserver(ClockObserver* observer) {
   clock_observers_.AddObserver(observer);
 }
 
 void SystemTrayNotifier::RemoveClockObserver(ClockObserver* observer) {
   clock_observers_.RemoveObserver(observer);
 }
 
 void SystemTrayNotifier::AddIMEObserver(IMEObserver* observer) {
   ime_observers_.AddObserver(observer);
@@ skipping 334 matching lines @@
 void SystemTrayNotifier::NotifyVirtualKeyboardSuppressionChanged(
     bool suppressed) {
   FOR_EACH_OBSERVER(VirtualKeyboardObserver,
                     virtual_keyboard_observers_,
                     OnKeyboardSuppressionChanged(suppressed));
 }
 
 #endif  // OS_CHROMEOS
 
 }  // namespace ash