Add SystemTrayObservers

ash/system/tray/system_tray_delegate.h

 // 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.
 
 #ifndef ASH_SYSTEM_TRAY_SYSTEM_TRAY_DELEGATE_H_
 #define ASH_SYSTEM_TRAY_SYSTEM_TRAY_DELEGATE_H_
 
 #include <string>
 #include <vector>
 
 #include "ash/ash_export.h"
+#include "ash/system/locale/locale_observer.h"
 #include "ash/system/power/power_supply_status.h"
 #include "ash/system/user/login_status.h"
 #include "base/file_path.h"
 #include "base/i18n/time_formatting.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/string16.h"
 #include "ui/gfx/image/image_skia.h"
 
 namespace ash {
 
+class SystemTrayObservers;
+
 struct ASH_EXPORT NetworkIconInfo {
   NetworkIconInfo();
   ~NetworkIconInfo();
 
   bool highlight;
   bool tray_icon_visible;
   gfx::ImageSkia image;
   string16 name;
   string16 description;
   std::string service_path;
@@ skipping 68 matching lines @@
 
 class VolumeControlDelegate;
 
 class SystemTrayDelegate {
  public:
   virtual ~SystemTrayDelegate() {}
 
   // Called after SystemTray has been instantiated.
   virtual void Initialize() = 0;
 
+  // Returns a SystemTrayObservers, or NULL of observers are not implemented.
+  virtual SystemTrayObservers* GetSystemTrayObservers() = 0;
+
   // Returns true if system tray should be visible on startup.
   virtual bool GetTrayVisibilityOnStartup() = 0;
 
   // Gets information about the logged in user.
   virtual const string16 GetUserDisplayName() const = 0;
   virtual const std::string GetUserEmail() const = 0;
   virtual const gfx::ImageSkia& GetUserImage() const = 0;
   virtual user::LoginStatus GetUserLoginStatus() const = 0;
 
   // Returns whether a system upgrade is available.
@@ skipping 169 matching lines @@
   virtual void SetVolumeControlDelegate(
       scoped_ptr<VolumeControlDelegate> delegate) = 0;
 
   // Creates a dummy delegate for testing.
   static SystemTrayDelegate* CreateDummyDelegate();
 };
 
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_TRAY_SYSTEM_TRAY_DELEGATE_H_