Adds the source ImageLoadingTracker to OnImageLoaded. I need this in a

chrome/browser/cocoa/extensions/browser_action_button.mm

 // 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.
 
 #import "chrome/browser/cocoa/extensions/browser_action_button.h"
 
 #include "app/gfx/canvas_paint.h"
 #include "base/sys_string_conversions.h"
 #include "chrome/browser/cocoa/extensions/extension_action_context_menu.h"
 #include "chrome/browser/extensions/image_loading_tracker.h"
@@ skipping 37 matching lines @@
     registrar_.Add(this, NotificationType::EXTENSION_BROWSER_ACTION_UPDATED,
                    Source<ExtensionAction>(extension->browser_action()));
   }
 
   ~ExtensionImageTrackerBridge() {
     if (tracker_)
       tracker_->StopTrackingImageLoad();
   }
 
   // ImageLoadingTracker::Observer implementation.
-  void OnImageLoaded(SkBitmap* image, size_t index) {
+  void OnImageLoaded(ImageLoadingTracker* source, SkBitmap* image,
+                     size_t index) {
     if (image)
       [owner_ setDefaultIcon:gfx::SkBitmapToNSImage(*image)];
     tracker_ = NULL;
     [owner_ updateState];
   }
 
   // Overridden from NotificationObserver.
   void Observe(NotificationType type,
                const NotificationSource& source,
                const NotificationDetails& details) {
@@ skipping 119 matching lines @@
     extensionAction_->PaintBadge(&canvas, boundingRect, tabId_);
   }
 
   [NSGraphicsContext restoreGraphicsState];
 }
 
 @synthesize tabId = tabId_;
 @synthesize extensionAction = extensionAction_;
 
 @end