Add ImeMenuTray element.

ash/system/chromeos/ime_menu/ime_menu_tray.h

+// Copyright 2016 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_CHROMEOS_IME_MENU_IME_MENU_TRAY_H_
+#define ASH_SYSTEM_CHROMEOS_IME_MENU_IME_MENU_TRAY_H_
+
+#include "ash/ash_export.h"
+#include "ash/common/system/ime/ime_observer.h"
+#include "ash/common/system/tray/system_tray_delegate.h"
+#include "ash/common/system/tray/tray_background_view.h"
+#include "ash/common/wm/window_state_observer.h"
+#include "base/macros.h"
+
+namespace views {
+class Label;
+}
+
+namespace ash {
+class StatusAreaWidget;
+
+class ASH_EXPORT ImeMenuTray : public TrayBackgroundView,
+                               public IMEObserver,
+                               public wm::WindowStateObserver {
+ public:
+  explicit ImeMenuTray(StatusAreaWidget* status_area_widget);
+  ~ImeMenuTray() override;
+
+  // Sets the window state of the IME menu AppWindow.
+  void SetWindowState(wm::WindowState* window_state);

[sky, 2016/06/30 16:21:39]

WindowState is owned by the corresponding window. How do you ensure you reset
window_state_ if the window is destroyed? I recommend changing this to
SetImeWindow() and attaching an observer to it. Once you have the window you can
get the windowstate if needed. I believe if you did this you wouldn't need to
change ExtensionAppWindowLauncherController::UnregisterApp either.

[Azure Wei, 2016/06/30 17:45:01]

Changed the method SetWindowState(wm::WindowState* window_state) with
SetImeWindow(aura::Window). And make ImeMenuTray listen on the window behaviour
directly. 

+
+  // TrayBackgroundView:
+  void SetShelfAlignment(ShelfAlignment alignment) override;
+  base::string16 GetAccessibleNameForTray() override;
+  void HideBubbleWithView(const views::TrayBubbleView* bubble_view) override;
+  void ClickedOutsideBubble() override;
+  bool PerformAction(const ui::Event& event) override;
+
+  // IMEObserver:
+  void OnIMERefresh() override;
+  void OnIMEMenuActivationChanged(bool is_activated) override;
+
+  // wm::WindowStateObserver:
+  void OnPostWindowStateTypeChange(wm::WindowState* window_state,
+                                   wm::WindowStateType old_type) override;
+
+ private:
+  // To allow the test class to access GetLabelTextForTest() method.
+  friend class ImeMenuTrayTest;
+
+  // Updates the UI of the IME menu tray.
+  void UpdateTray();
+
+  // Sets the border of the label to keep the tray width consistant.
+  void SetLabelBorder();
+
+  views::Label* label_;
+  ash::wm::WindowState* window_state_;
+  ash::IMEInfo current_ime_;
+
+  DISALLOW_COPY_AND_ASSIGN(ImeMenuTray);
+};
+
+}  // namespace ash
+
+#endif  // ASH_SYSTEM_CHROMEOS_IME_MENU_IME_MENU_TRAY_H_