Update browser actions api to be like new design doc.

chrome/browser/extensions/image_loading_tracker.cc

 // Copyright (c) 2009 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.
 
 #include "chrome/browser/extensions/image_loading_tracker.h"
 
 #include "app/gfx/favicon_size.h"
 #include "base/file_util.h"
 #include "base/logging.h"
 #include "base/message_loop.h"
@@ skipping 20 matching lines @@
   // identifier for the image that we pass back to the caller.
   LoadImageTask(ImageLoadingTracker* tracker,
                 const ExtensionResource& resource,
                 size_t index)
     : callback_loop_(MessageLoop::current()),
       tracker_(tracker),
       resource_(resource),
       index_(index) {}
 
   void ReportBack(SkBitmap* image) {
-    DCHECK(image);
     callback_loop_->PostTask(FROM_HERE, NewRunnableMethod(tracker_,
         &ImageLoadingTracker::OnImageLoaded,
         image,
         index_));
   }
 
   virtual void Run() {
     // Read the file from disk.
     std::string file_contents;
     FilePath path = resource_.GetFilePath();
@@ skipping 44 matching lines @@
 ////////////////////////////////////////////////////////////////////////////////
 // ImageLoadingTracker
 
 void ImageLoadingTracker::PostLoadImageTask(const ExtensionResource& resource) {
   MessageLoop* file_loop = g_browser_process->file_thread()->message_loop();
   file_loop->PostTask(FROM_HERE, new LoadImageTask(this, resource,
                                                    posted_count_++));
 }
 
 void ImageLoadingTracker::OnImageLoaded(SkBitmap* image, size_t index) {
-  if (image == NULL) {
-    NOTREACHED() << "Image failed to decode.";
-    image = new SkBitmap();
-  }
   if (observer_)
     observer_->OnImageLoaded(image, index);
-  delete image;
+
+  if (image)
+    delete image;
+
   if (--image_count_ == 0)
     Release();  // We are no longer needed.
 }