Fix uber tray to accept focus via tab selection

ash/system/tray/system_tray.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_H_
 #define ASH_SYSTEM_TRAY_SYSTEM_TRAY_H_
 #pragma once
 
 #include "ash/launcher/background_animator.h"
 #include "ash/ash_export.h"
@@ skipping 61 matching lines @@
   void UpdateAfterLoginStatusChange(user::LoginStatus login_status);
 
   const ScopedVector<SystemTrayItem>& items() const { return items_; }
 
   // Sets whether the tray paints a background. Default is true, but is set to
   // false if a window overlaps the shelf.
   void SetPaintsBackground(
       bool value,
       internal::BackgroundAnimator::ChangeType change_type);
 
+  // Take focus and activate the system tray.
+  void TakeFocus(View* next_focusable_view);
+
   // Returns true if the launcher should show.
   bool should_show_launcher() const { return popup_ && should_show_launcher_; }
+  bool is_taking_focus() const { return taking_focus_; }
 
   AccessibilityObserver* accessibility_observer() const {
     return accessibility_observer_;
   }
   AudioObserver* audio_observer() const {
     return audio_observer_;
   }
   BluetoothObserver* bluetooth_observer() const {
     return bluetooth_observer_;
   }
@@ skipping 73 matching lines @@
   // The popup widget and the delegate.
   internal::SystemTrayBubble* bubble_;
   views::Widget* popup_;
 
   // Owned by the view it's installed on.
   internal::SystemTrayBackground* background_;
 
   // See description agove getter.
   bool should_show_launcher_;
 
+  // Set when taking focus to indicate that the system area can be activated.
+  bool taking_focus_;
+
   internal::BackgroundAnimator hide_background_animator_;
   internal::BackgroundAnimator hover_background_animator_;
 
   DISALLOW_COPY_AND_ASSIGN(SystemTray);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_TRAY_SYSTEM_TRAY_H_