Revert of Do not activate TrayBubbleView by default

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_
 
 #include <map>
 #include <memory>
 #include <vector>
 
 #include "ash/ash_export.h"
 #include "ash/system/tray/system_tray_bubble.h"
 #include "ash/system/tray/tray_background_view.h"
 #include "base/macros.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 TrayEnterprise;
 class TrayNetwork;
@@ skipping 94 matching lines @@
   void AnchorUpdated() override;
   base::string16 GetAccessibleNameForTray() override;
   void BubbleResized(const views::TrayBubbleView* bubble_view) override;
   void HideBubbleWithView(const views::TrayBubbleView* bubble_view) override;
   void ClickedOutsideBubble() override;
 
   // views::TrayBubbleView::Delegate:
   void BubbleViewDestroyed() override;
   void OnMouseEnteredView() override;
   void OnMouseExitedView() override;
-  void RegisterAccelerators(const std::vector<ui::Accelerator>& accelerators,
-                            views::TrayBubbleView* tray_bubble_view) override;
-  void UnregisterAllAccelerators(
-      views::TrayBubbleView* tray_bubble_view) override;
   base::string16 GetAccessibleNameForBubble() override;
-  bool ShouldEnableExtraKeyboardAccessibility() override;
   void HideBubble(const views::TrayBubbleView* bubble_view) override;
 
   ScreenTrayItem* GetScreenShareItem() { return screen_share_tray_item_; }
   ScreenTrayItem* GetScreenCaptureItem() { return screen_capture_tray_item_; }
 
   // Activates the system tray bubble.
   void ActivateBubble();
 
  private:
   friend class SystemTrayTestApi;
   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. See |ShowItems()| for why key events are
+  // observed.
+  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();
 
   // Returns a string with the current time for accessibility on the status
   // tray bar.
   base::string16 GetAccessibleTimeString(const base::Time& now) const;
 
@@ skipping 56 matching lines @@
   TraySessionLengthLimit* tray_session_length_limit_ = nullptr;
   TraySupervisedUser* tray_supervised_user_ = nullptr;
   TraySystemInfo* tray_system_info_ = nullptr;
   TrayUpdate* tray_update_ = nullptr;
   TrayNightLight* tray_night_light_ = nullptr;
 
   // A reference to the Screen share and capture item.
   ScreenTrayItem* screen_capture_tray_item_ = nullptr;  // not owned
   ScreenTrayItem* screen_share_tray_item_ = nullptr;    // not owned
 
+  std::unique_ptr<KeyEventWatcher> key_event_watcher_;
+
   std::unique_ptr<ActivationObserver> activation_observer_;
 
   DISALLOW_COPY_AND_ASSIGN(SystemTray);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_TRAY_SYSTEM_TRAY_H_