Revert of ash: Use system tray mojo interface to show system update tray icon

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/date/clock_observer.h"
 #include "ash/common/system/ime/ime_observer.h"
+#include "ash/common/system/update/update_observer.h"
 #include "ash/common/system/user/user_observer.h"
 
 #if defined(OS_CHROMEOS)
 #include "ash/common/system/chromeos/bluetooth/bluetooth_observer.h"
 #include "ash/common/system/chromeos/enterprise/enterprise_domain_observer.h"
 #include "ash/common/system/chromeos/media_security/media_capture_observer.h"
 #include "ash/common/system/chromeos/network/network_observer.h"
 #include "ash/common/system/chromeos/network/network_portal_detector_observer.h"
 #include "ash/common/system/chromeos/screen_security/screen_capture_observer.h"
 #include "ash/common/system/chromeos/screen_security/screen_share_observer.h"
@@ skipping 65 matching lines @@
 void SystemTrayNotifier::NotifyRefreshIME() {
   for (auto& observer : ime_observers_)
     observer.OnIMERefresh();
 }
 
 void SystemTrayNotifier::NotifyRefreshIMEMenu(bool is_active) {
   for (auto& observer : ime_observers_)
     observer.OnIMEMenuActivationChanged(is_active);
 }
 
+void SystemTrayNotifier::AddUpdateObserver(UpdateObserver* observer) {
+  update_observers_.AddObserver(observer);
+}
+
+void SystemTrayNotifier::RemoveUpdateObserver(UpdateObserver* observer) {
+  update_observers_.RemoveObserver(observer);
+}
+
+void SystemTrayNotifier::NotifyUpdateRecommended(const UpdateInfo& info) {
+  for (auto& observer : update_observers_)
+    observer.OnUpdateRecommended(info);
+}
+
 void SystemTrayNotifier::AddUserObserver(UserObserver* observer) {
   user_observers_.AddObserver(observer);
 }
 
 void SystemTrayNotifier::RemoveUserObserver(UserObserver* observer) {
   user_observers_.RemoveObserver(observer);
 }
 
 void SystemTrayNotifier::NotifyUserUpdate() {
   for (auto& observer : user_observers_)
@@ skipping 210 matching lines @@
 
 void SystemTrayNotifier::NotifyVirtualKeyboardSuppressionChanged(
     bool suppressed) {
   for (auto& observer : virtual_keyboard_observers_)
     observer.OnKeyboardSuppressionChanged(suppressed);
 }
 
 #endif  // defined(OS_CHROMEOS)
 
 }  // namespace ash