Add a button on status bar to indicate that accessibility is enabled.

chrome/browser/chromeos/status/accessibility_menu_button.h

+// Copyright (c) 2011 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 CHROME_BROWSER_CHROMEOS_STATUS_ACCESSIBILITY_MENU_BUTTON_H_
+#define CHROME_BROWSER_CHROMEOS_STATUS_ACCESSIBILITY_MENU_BUTTON_H_
+#pragma once
+
+#include "chrome/browser/chromeos/status/status_area_button.h"
+#include "chrome/browser/prefs/pref_member.h"
+#include "content/common/notification_observer.h"
+#include "views/controls/menu/view_menu_delegate.h"
+#include "views/controls/menu/menu_delegate.h"
+
+namespace views {
+class MenuRunner;
+}
+
+namespace chromeos {
+
+class StatusAreaHost;
+
+// A class for the button in the status area which alerts the user when
+// accessibility features are enabled.
+class AccessibilityMenuButton : public StatusAreaButton,
+                                public views::ViewMenuDelegate,
+                                public views::MenuDelegate,
+                                public NotificationObserver {
+ public:
+  explicit AccessibilityMenuButton(StatusAreaHost* host);
+  virtual ~AccessibilityMenuButton();
+
+  // views::ViewMenuDelegate implementation
+  virtual void RunMenu(views::View* source, const gfx::Point& pt) OVERRIDE;
+
+  // views::MenuDelegate implementation
+  virtual void ExecuteCommand(int id) OVERRIDE;
+
+  // NotificationObserver implementation
+  virtual void Observe(int type,
+                       const NotificationSource& source,
+                       const NotificationDetails& details) OVERRIDE;
+
+ private:
+  // Updates the state along with the preferences.
+  void Update();
+
+  // Prepares menu before showing it.
+  void PrepareMenu();
+
+  // An object synced to the preference, representing if accessibility feature
+  // is enabled or not.
+  BooleanPrefMember accessibility_enabled_;
+  // An object to show menu.
+  scoped_ptr<views::MenuRunner> menu_runner_;
+
+  DISALLOW_COPY_AND_ASSIGN(AccessibilityMenuButton);
+};
+
+}  // namespace chromeos
+
+#endif  // CHROME_BROWSER_CHROMEOS_STATUS_ACCESSIBILITY_MENU_BUTTON_H_