Do not activate system tray bubble by default

ash/common/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_COMMON_SYSTEM_TRAY_SYSTEM_TRAY_H_
 #define ASH_COMMON_SYSTEM_TRAY_SYSTEM_TRAY_H_
 
 #include <map>
 #include <memory>
 #include <vector>
 
 #include "ash/ash_export.h"
 #include "ash/common/system/tray/system_tray_bubble.h"
 #include "ash/common/system/tray/tray_background_view.h"
 #include "base/macros.h"
 #include "base/memory/scoped_vector.h"
 #include "ui/views/bubble/tray_bubble_view.h"
 #include "ui/views/view.h"
 
 namespace ash {
 
+class KeyEventWatcher;
 enum class LoginStatus;
 class ScreenTrayItem;
 class SystemBubbleWrapper;
 class SystemTrayDelegate;
 class SystemTrayItem;
 class TrayAccessibility;
 class TrayAudio;
 class TrayCast;
 class TrayDate;
 class TrayUpdate;
@@ skipping 128 matching lines @@
     return tray_accessibility_;
   }
 
   // Get the tray item view (or NULL) for a given |tray_item| in a unit test.
   views::View* GetTrayItemViewForTest(SystemTrayItem* tray_item);
 
   TrayCast* GetTrayCastForTesting() const;
   TrayDate* GetTrayDateForTesting() const;
   TrayUpdate* GetTrayUpdateForTesting() const;
 
+  // Activates the system tray bubble.
+  void ActivateBubble();
+
  private:
+  class ActivationObserver;
+
+  // Closes the bubble. Used to bind as a KeyEventWatcher::KeyEventCallback.
+  void CloseBubble(const ui::KeyEvent& key_event);
+
+  // Activates the bubble and starts key navigation with the |key_event|.
+  void ActivateAndStartNavigation(const ui::KeyEvent& key_event);
+
+  // Creates the key event watcher.

[James Cook, 2016/09/23 16:32:28]

nit: "See ShowItems() for why key events are observed."

[oshima, 2016/09/23 19:19:54]

Done.

+  void CreateKeyEventWatcher();
+
   // Creates the default set of items for the sytem tray.
   void CreateItems(SystemTrayDelegate* delegate);
 
   // Resets |system_bubble_| and clears any related state.
   void DestroySystemBubble();
 
   // Resets |notification_bubble_| and clears any related state.
   void DestroyNotificationBubble();
 
   // Returns a string with the current time for accessibility on the status
   // tray bar.
   base::string16 GetAccessibleTimeString(const base::Time& now) const;
 
   // Calculates the x-offset for the item in the tray. Returns -1 if its tray
   // item view is not visible.
   int GetTrayXOffset(SystemTrayItem* item) const;
 
   // Shows the default view and its arrow position is shifted by |x_offset|.
   void ShowDefaultViewWithOffset(BubbleCreationType creation_type,
                                  int x_offset,
                                  bool persistent);
 
   // Constructs or re-constructs |system_bubble_| and populates it with |items|.
   // Specify |change_tray_status| to true if want to change the tray background
-  // status.
+  // status. The bubble will be opened in inactive state. If |can_activate| is
+  // true, the bubble will be activated by one of following means.
+  // * When alt/alt-tab acclerator is used to start navigation.
+  // * When the bubble is opened by accelerator.
+  // * When the tray item is set to be focused.

[James Cook, 2016/09/23 16:32:28]

Nice documentation.

   void ShowItems(const std::vector<SystemTrayItem*>& items,
                  bool details,
-                 bool activate,
+                 bool can_activate,
                  BubbleCreationType creation_type,
                  int x_offset,
                  bool persistent);
 
   // Constructs or re-constructs |notification_bubble_| and populates it with
   // |notification_items_|, or destroys it if there are no notification items.
   void UpdateNotificationBubble();
 
   // Checks the current status of the system tray and updates the web
   // notification tray according to the current status.
@@ skipping 47 matching lines @@
   TrayAccessibility* tray_accessibility_;
   TrayAudio* tray_audio_;  // May be null.
   TrayCast* tray_cast_;
   TrayDate* tray_date_;
   TrayUpdate* tray_update_;
 
   // A reference to the Screen share and capture item.
   ScreenTrayItem* screen_capture_tray_item_;  // not owned
   ScreenTrayItem* screen_share_tray_item_;    // not owned
 
+  std::unique_ptr<KeyEventWatcher> key_event_watcher_;
+
+  std::unique_ptr<ActivationObserver> activation_observer_;
+
   DISALLOW_COPY_AND_ASSIGN(SystemTray);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_SYSTEM_TRAY_SYSTEM_TRAY_H_