Eliminate all UI thread decoding of extension images....

chrome/browser/views/infobars/extension_infobar.h

 // Copyright (c) 2010 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_VIEWS_INFOBARS_EXTENSION_INFOBAR_H_
 #define CHROME_BROWSER_VIEWS_INFOBARS_EXTENSION_INFOBAR_H_
 
 #include "chrome/browser/views/infobars/infobars.h"
 
+#include "chrome/browser/extensions/image_loading_tracker.h"
 #include "chrome/browser/views/extensions/extension_view.h"
 #include "views/controls/menu/view_menu_delegate.h"
 
 class ExtensionContextMenuModel;
 class ExtensionInfoBarDelegate;
 
 namespace views {
   class MenuButton;
   class Menu2;
 }
 
 // This class implements InfoBars for Extensions.
 class ExtensionInfoBar : public InfoBar,
                          public ExtensionView::Container,
+                         public ImageLoadingTracker::Observer,
                          public views::ViewMenuDelegate {
  public:
   explicit ExtensionInfoBar(ExtensionInfoBarDelegate* delegate);
   virtual ~ExtensionInfoBar();
 
   // Overridden from ExtensionView::Container:
   virtual void OnExtensionMouseEvent(ExtensionView* view) {}
   virtual void OnExtensionMouseLeave(ExtensionView* view) {}
   virtual void OnExtensionPreferredSizeChanged(ExtensionView* view);
 
   // Overridden from views::View:
   virtual void Layout();
 
+  // Overridden from ImageLoadingTracker::Observer:
+  virtual void OnImageLoaded(
+      SkBitmap* image, ExtensionResource resource, int index);
+
   // Overridden from views::ViewMenuDelegate:
   virtual void RunMenu(View* source, const gfx::Point& pt);
 
  private:
   // Setup the menu button showing the small extension icon and its dropdown
   // menu.
   void SetupIconAndMenu();
 
   NotificationRegistrar notification_registrar_;
 
   ExtensionInfoBarDelegate* delegate_;
 
   // The dropdown menu for accessing the contextual extension actions.
   scoped_ptr<ExtensionContextMenuModel> options_menu_contents_;
   scoped_ptr<views::Menu2> options_menu_menu_;
   views::MenuButton* menu_;
 
+  // Keeps track of images being loaded on the File thread.
+  ImageLoadingTracker tracker_;
+
   DISALLOW_COPY_AND_ASSIGN(ExtensionInfoBar);
 };
 
 #endif  // CHROME_BROWSER_VIEWS_INFOBARS_EXTENSION_INFOBAR_H_