Do not activate system tray bubble by default

ash/common/system/tray/tray_item_more.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_COMMON_SYSTEM_TRAY_TRAY_ITEM_MORE_H_
 #define ASH_COMMON_SYSTEM_TRAY_TRAY_ITEM_MORE_H_
 
 #include "ash/common/system/tray/actionable_view.h"
 #include "base/macros.h"
 #include "ui/views/view.h"
 
 namespace views {
 class ImageView;
 class Label;
 class View;
 }
 
 namespace ash {
 class SystemTrayItem;
 
 // A view with a chevron ('>') on the right edge. Clicking on the view brings up
 // the detailed view of the tray-item that owns it.
 class TrayItemMore : public ActionableView {
  public:
   TrayItemMore(SystemTrayItem* owner, bool show_more);
   ~TrayItemMore() override;
 
-  SystemTrayItem* owner() const { return owner_; }
-
   void SetLabel(const base::string16& label);
   void SetImage(const gfx::ImageSkia& image_skia);
   void SetAccessibleName(const base::string16& name);
 
  private:
   // TODO(bruthig): Re-design to inform subclasses when the style changes while
   // avoiding virtual function calls from the constructor.
   void UpdateStyle();
 
   // Overridden from ActionableView.
   bool PerformAction(const ui::Event& event) override;
 
   // Overridden from views::View.
   void Layout() override;
   void GetAccessibleState(ui::AXViewState* state) override;
   void OnNativeThemeChanged(const ui::NativeTheme* theme) override;
 
-  SystemTrayItem* owner_;
   // True if |more_| should be shown.
   bool show_more_;
   views::ImageView* icon_;
   views::Label* label_;
   views::ImageView* more_;
   base::string16 accessible_name_;
 
   DISALLOW_COPY_AND_ASSIGN(TrayItemMore);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_SYSTEM_TRAY_TRAY_ITEM_MORE_H_