Use mojo SystemTray interfaces for both mash and classic ash

ash/common/system/tray/system_tray_notifier.cc

 // Copyright 2016 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/common/system/tray/system_tray_notifier.h"
 
 #include "ash/common/system/accessibility_observer.h"
 #include "ash/common/system/audio/audio_observer.h"
 #include "ash/common/system/date/clock_observer.h"
 #include "ash/common/system/ime/ime_observer.h"
@@ skipping 64 matching lines @@
 void SystemTrayNotifier::NotifyAudioActiveOutputNodeChanged() {
   FOR_EACH_OBSERVER(AudioObserver, audio_observers_,
                     OnActiveOutputNodeChanged());
 }
 
 void SystemTrayNotifier::NotifyAudioActiveInputNodeChanged() {
   FOR_EACH_OBSERVER(AudioObserver, audio_observers_,
                     OnActiveInputNodeChanged());
 }
 
-void SystemTrayNotifier::AddClockObserver(ClockObserver* observer) {
-  clock_observers_.AddObserver(observer);
-}
-
-void SystemTrayNotifier::RemoveClockObserver(ClockObserver* observer) {
-  clock_observers_.RemoveObserver(observer);
-}
-
 void SystemTrayNotifier::NotifyRefreshClock() {
   FOR_EACH_OBSERVER(ClockObserver, clock_observers_, Refresh());
 }
 
-void SystemTrayNotifier::NotifyDateFormatChanged() {
-  FOR_EACH_OBSERVER(ClockObserver, clock_observers_, OnDateFormatChanged());
-}
-
 void SystemTrayNotifier::NotifySystemClockTimeUpdated() {
   FOR_EACH_OBSERVER(ClockObserver, clock_observers_,
                     OnSystemClockTimeUpdated());
 }
 
 void SystemTrayNotifier::NotifySystemClockCanSetTimeChanged(bool can_set_time) {
   FOR_EACH_OBSERVER(ClockObserver, clock_observers_,
                     OnSystemClockCanSetTimeChanged(can_set_time));
 }
 
@@ skipping 263 matching lines @@
 
 void SystemTrayNotifier::NotifyVirtualKeyboardSuppressionChanged(
     bool suppressed) {
   FOR_EACH_OBSERVER(VirtualKeyboardObserver, virtual_keyboard_observers_,
                     OnKeyboardSuppressionChanged(suppressed));
 }
 
 #endif  // defined(OS_CHROMEOS)
 
 }  // namespace ash