Fix uber tray crash on stumpy which has no battery

ash/system/settings/tray_settings.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/settings/tray_settings.h"
 
 #include "ash/shell.h"
 #include "ash/system/power/power_status_view.h"
 #include "ash/system/tray/system_tray_delegate.h"
 #include "ash/system/tray/tray_constants.h"
@@ skipping 51 matching lines @@
       power_status_view_ = new ash::internal::PowerStatusView(
           ash::internal::PowerStatusView::VIEW_DEFAULT, power_view_right_align);
       AddChildView(power_status_view_);
       UpdatePowerStatus(power_status);
     }
   }
 
   virtual ~SettingsDefaultView() {}
 
   void UpdatePowerStatus(const PowerSupplyStatus& status) {
-    if (power_status_view_)
-      power_status_view_->UpdatePowerStatus(status);
+    if (!power_status_view_)
+      return;
+    power_status_view_->UpdatePowerStatus(status);
     string16 accessible_name = label_ ?
         label_->text() + ASCIIToUTF16(", ") +
             power_status_view_->accessible_name() :
         power_status_view_->accessible_name();
     SetAccessibleName(accessible_name);
   }
 
   // Overridden from ash::internal::ActionableView.
   virtual bool PerformAction(const ui::Event& event) OVERRIDE {
     if (login_status_ == user::LOGGED_IN_NONE ||
@@ skipping 76 matching lines @@
 }
 
 // Overridden from PowerStatusObserver.
 void TraySettings::OnPowerStatusChanged(const PowerSupplyStatus& status) {
   if (default_view_)
     default_view_->UpdatePowerStatus(status);
 }
 
 }  // namespace internal
 }  // namespace ash