content: convert zoom notifications to observer usage

chrome/browser/ui/toolbar/wrench_menu_model.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 CHROME_BROWSER_UI_TOOLBAR_WRENCH_MENU_MODEL_H_
 #define CHROME_BROWSER_UI_TOOLBAR_WRENCH_MENU_MODEL_H_
 
 #include "base/file_path.h"
 #include "base/memory/scoped_ptr.h"
 #include "chrome/browser/ui/tabs/tab_strip_model_observer.h"
+#include "content/public/browser/host_zoom_map.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 #include "ui/base/accelerators/accelerator.h"
 #include "ui/base/models/button_menu_item_model.h"
 #include "ui/base/models/simple_menu_model.h"
 
 class BookmarkSubMenuModel;
 class Browser;
 class RecentTabsSubMenuModel;
 class TabStripModel;
@@ skipping 119 matching lines @@
   // clipboard menu content and the finalizing menu break. If the last break
   // is not needed it can be suppressed by setting |new_menu|
   // to false.
   void CreateCutCopyPasteMenu(bool new_menu);
 
   // Appends everything needed for the zoom menu: a menu break, then the zoom
   // menu content and then another menu break. If the new menu type is used,
   // |new_menu| should be set to true.
   void CreateZoomMenu(bool new_menu);
 
+  void OnZoomLevelChanged(const std::string& host);
+
   // Models for the special menu items with buttons.
   scoped_ptr<ui::ButtonMenuItemModel> edit_menu_item_model_;
   scoped_ptr<ui::ButtonMenuItemModel> zoom_menu_item_model_;
 
   // Label of the zoom label in the zoom menu item.
   string16 zoom_label_;
 
   // Tools menu.
   scoped_ptr<ToolsMenuModel> tools_menu_model_;
 
   // Bookmark submenu.
   scoped_ptr<BookmarkSubMenuModel> bookmark_sub_menu_model_;
 
   // Recent Tabs submenu.
   scoped_ptr<RecentTabsSubMenuModel> recent_tabs_sub_menu_model_;
 
   ui::AcceleratorProvider* provider_;  // weak
 
   Browser* browser_;  // weak
   TabStripModel* tab_strip_model_; // weak
 
+  content::HostZoomMap::ZoomLevelChangedCallback zoom_callback_;
   content::NotificationRegistrar registrar_;
 
   DISALLOW_COPY_AND_ASSIGN(WrenchMenuModel);
 };
 
 #endif  // CHROME_BROWSER_UI_TOOLBAR_WRENCH_MENU_MODEL_H_