Revert of Do not activate TrayBubbleView by default

ash/system/tray/system_tray_bubble.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_BUBBLE_H_
 #define ASH_SYSTEM_TRAY_SYSTEM_TRAY_BUBBLE_H_
 
 #include <map>
 #include <memory>
 #include <vector>
@@ skipping 20 matching lines @@
   // Change the items displayed in the bubble.
   void UpdateView(const std::vector<ash::SystemTrayItem*>& items,
                   BubbleType bubble_type);
 
   // Creates |bubble_view_| and a child views for each member of |items_|.
   // Also creates |bubble_wrapper_|. |init_params| may be modified.
   void InitView(views::View* anchor,
                 LoginStatus login_status,
                 views::TrayBubbleView::InitParams* init_params);
 
+  // Focus the default item if no item is focused. Othewise, do nothing.
+  void FocusDefaultIfNeeded();
+
   BubbleType bubble_type() const { return bubble_type_; }
   views::TrayBubbleView* bubble_view() const { return bubble_view_; }
 
   void DestroyItemViews();
   void BubbleViewDestroyed();
   void StartAutoCloseTimer(int seconds);
   void StopAutoCloseTimer();
   void RestartAutoCloseTimer();
   void Close();
   void SetVisible(bool is_visible);
@@ skipping 23 matching lines @@
 
   int autoclose_delay_;
   base::OneShotTimer autoclose_;
 
   DISALLOW_COPY_AND_ASSIGN(SystemTrayBubble);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_TRAY_SYSTEM_TRAY_BUBBLE_H_