Add SystemTrayObservers

ash/system/tray/test_system_tray_delegate.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/test_system_tray_delegate.h"
 
 #include "ash/shell.h"
 #include "ash/volume_control_delegate.h"
 #include "base/utf_string_conversions.h"
 #include "base/message_loop.h"
@@ skipping 44 matching lines @@
       volume_control_delegate_(
           ALLOW_THIS_IN_INITIALIZER_LIST(new TestVolumeControlDelegate)) {
 }
 
 TestSystemTrayDelegate::~TestSystemTrayDelegate() {
 }
 
 void TestSystemTrayDelegate::Initialize() {
 }
 
+SystemTrayObservers* TestSystemTrayDelegate::GetSystemTrayObservers() {
+  return NULL;
+}
+
 bool TestSystemTrayDelegate::GetTrayVisibilityOnStartup() {
   return true;
 }
 
 // Overridden from SystemTrayDelegate:
 const string16 TestSystemTrayDelegate::GetUserDisplayName() const {
   return UTF8ToUTF16("Über tray Über tray Über tray Über tray");
 }
 
 const std::string TestSystemTrayDelegate::GetUserEmail() const {
@@ skipping 203 matching lines @@
   return volume_control_delegate_.get();
 }
 
 void TestSystemTrayDelegate::SetVolumeControlDelegate(
     scoped_ptr<VolumeControlDelegate> delegate) {
   volume_control_delegate_ = delegate.Pass();
 }
 
 }  // namespace test
 }  // namespace ash