Add notification mechanism when BrowserActionButton's icon has been updated.

chrome/browser/ui/views/toolbar/browser_action_view.h

 // Copyright 2013 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_VIEWS_TOOLBAR_BROWSER_ACTION_VIEW_H_
 #define CHROME_BROWSER_UI_VIEWS_TOOLBAR_BROWSER_ACTION_VIEW_H_
 
 #include <string>
 
 #include "chrome/browser/extensions/extension_action_icon_factory.h"
@@ skipping 93 matching lines @@
 
 // The BrowserActionButton is a specialization of the MenuButton class.
 // It acts on a ExtensionAction, in this case a BrowserAction and handles
 // loading the image for the button asynchronously on the file thread.
 class BrowserActionButton : public views::MenuButton,
                             public views::ButtonListener,
                             public views::ContextMenuController,
                             public content::NotificationObserver,
                             public ExtensionActionIconFactory::Observer {
  public:
+  // The IconObserver will receive a notification when the button's icon has
+  // been updated.
+  class IconObserver {
+   public:
+    virtual ~IconObserver() {}
+    virtual void OnIconUpdated(const gfx::ImageSkia& icon) = 0;
+  };
+
+  void set_icon_observer(IconObserver* icon_observer) {
+    icon_observer_ = icon_observer;
+  }
+
   BrowserActionButton(const extensions::Extension* extension,
                       Browser* browser_,
                       BrowserActionView::Delegate* delegate);
 
   // Call this instead of delete.
   void Destroy();
 
   ExtensionAction* browser_action() const { return browser_action_; }
   const extensions::Extension* extension() { return extension_; }
 
@@ skipping 99 matching lines @@
 
   content::NotificationRegistrar registrar_;
 
   // The extension key binding accelerator this browser action is listening for
   // (to show the popup).
   scoped_ptr<ui::Accelerator> keybinding_;
 
   // Responsible for running the menu.
   scoped_ptr<views::MenuRunner> menu_runner_;
 
+  IconObserver* icon_observer_;

[Finnur, 2014/02/10 10:41:41]

nit: Document.

+
   friend class base::DeleteHelper<BrowserActionButton>;
 
   DISALLOW_COPY_AND_ASSIGN(BrowserActionButton);
 };
 
 #endif  // CHROME_BROWSER_UI_VIEWS_TOOLBAR_BROWSER_ACTION_VIEW_H_