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diff --git a/chrome/browser/extensions/image_loading_tracker.h b/chrome/browser/extensions/image_loading_tracker.h
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+++ b/chrome/browser/extensions/image_loading_tracker.h
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+// 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_EXTENSIONS_IMAGE_LOADING_TRACKER_H_
+#define CHROME_BROWSER_EXTENSIONS_IMAGE_LOADING_TRACKER_H_
+
+#include <map>
+
+#include "base/ref_counted.h"
+#include "chrome/common/notification_observer.h"
+#include "chrome/common/notification_registrar.h"
+
+class Extension;
+class ExtensionResource;
+class SkBitmap;
+
+namespace gfx {
+  class Size;
+}
+
+// The views need to load their icons asynchronously but might be deleted before
+// the images have loaded. This class encapsulates a loader class that stays
+// alive while the request is in progress (manages its own lifetime) and keeps
+// track of whether the view still cares about the icon loading.
+//
+// To use this class, have your class derive from ImageLoadingTracker::Observer,
+// and add a member variable ImageLoadingTracker tracker_. Then override
+// Observer::OnImageLoaded and call:
+//   tracker_.LoadImage(extension, resource, max_size, false);
+// ... and wait for OnImageLoaded to be called back on you with a pointer to the
+// SkBitmap loaded.
+// NOTE: if the image is available already (or the resource is not valid), the
+// Observer is notified immediately from the call to LoadImage. In other words,
+// by the time LoadImage returns the observer has been notified.
+//
+class ImageLoadingTracker : public NotificationObserver {
+ public:
+  enum CacheParam {
+    CACHE,
+    DONT_CACHE
+  };
+
+  class Observer {
+   public:
+    virtual ~Observer();
+
+    // Will be called when the image with the given index has loaded.
+    // The |image| is owned by the tracker, so the observer should make a copy
+    // if they need to access it after this call. |image| can be null if valid
+    // image was not found or it failed to decode. |resource| is the
+    // ExtensionResource where the |image| came from and the |index| represents
+    // the index of the image just loaded (starts at 0 and increments every
+    // time LoadImage is called).
+    virtual void OnImageLoaded(SkBitmap* image, ExtensionResource resource,
+                               int index) = 0;
+  };
+
+  explicit ImageLoadingTracker(Observer* observer);
+  ~ImageLoadingTracker();
+
+  // Specify image resource to load. If the loaded image is larger than
+  // |max_size| it will be resized to those dimensions.
+  void LoadImage(Extension* extension,
+                 const ExtensionResource& resource,
+                 const gfx::Size& max_size,
+                 CacheParam cache);
+
+ private:
+  typedef std::map<int, Extension*> LoadMap;
+
+  class ImageLoader;
+
+  // When an image has finished loaded and been resized on the file thread, it
+  // is posted back to this method on the original thread.  This method then
+  // calls the observer's OnImageLoaded and deletes the ImageLoadingTracker if
+  // it was the last image in the list. The |original_size| should be the size
+  // of the image before any resizing was done.
+  // |image| may be null if the file failed to decode.
+  void OnImageLoaded(SkBitmap* image, const ExtensionResource& resource,
+                     const gfx::Size& original_size, int id);
+
+  // NotificationObserver method. If an extension is uninstalled while we're
+  // waiting for the image we remove the entry from load_map_.
+  virtual void Observe(NotificationType type,
+                       const NotificationSource& source,
+                       const NotificationDetails& details);
+
+  // The view that is waiting for the image to load.
+  Observer* observer_;
+
+  // ID to use for next image requested. This is an ever increasing integer.
+  int next_id_;
+
+  // The object responsible for loading the image on the File thread.
+  scoped_refptr<ImageLoader> loader_;
+
+  // If LoadImage is told to cache the result an entry is added here. The
+  // integer identifies the id assigned to the request. If the extension is
+  // deleted while fetching the image the entry is removed from the map.
+  LoadMap load_map_;
+
+  NotificationRegistrar registrar_;
+
+  DISALLOW_COPY_AND_ASSIGN(ImageLoadingTracker);
+};
+
+#endif  // CHROME_BROWSER_EXTENSIONS_IMAGE_LOADING_TRACKER_H_