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diff --git a/extensions/browser/extension_icon_image.h b/extensions/browser/extension_icon_image.h
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+++ b/extensions/browser/extension_icon_image.h
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+// Copyright 2014 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 EXTENSIONS_BROWSER_EXTENSION_ICON_IMAGE_H_
+#define EXTENSIONS_BROWSER_EXTENSION_ICON_IMAGE_H_
+
+#include <map>
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/memory/weak_ptr.h"
+#include "content/public/browser/notification_observer.h"
+#include "content/public/browser/notification_registrar.h"
+#include "extensions/common/extension_icon_set.h"
+#include "ui/base/layout.h"
+#include "ui/gfx/image/image_skia.h"
+
+namespace content {
+class BrowserContext;
+}
+
+namespace extensions {
+class Extension;
+}
+
+namespace gfx {
+class Size;
+class Image;
+}
+
+namespace extensions {
+
+// A class that provides an ImageSkia for UI code to use. It handles extension
+// icon resource loading, screen scale factor change etc. UI code that uses
+// extension icon should host this class and be its observer. ExtensionIconImage
+// should be outlived by the observer. In painting code, UI code paints with the
+// ImageSkia provided by this class. If required extension icon resource is not
+// already present, this class tries to load it and calls its observer interface
+// when the image get updated. Until the resource is loaded, the UI code will be
+// provided with blank, transparent image.
+// If the requested resource doesn't exist or can't be loaded and a default
+// icon was supplied in the constructor, icon image will be updated with the
+// default icon's resource.
+// The default icon doesn't need to be supplied, but in that case, icon image
+// representation will be left blank if the resource loading fails.
+// If default icon is supplied, it is assumed that it contains or can
+// synchronously create (when |GetRepresentation| is called on it)
+// representations for all the scale factors supported by the current platform.
+// Note that |IconImage| is not thread safe.
+class IconImage : public content::NotificationObserver {
+ public:
+  class Observer {
+   public:
+    // Invoked when a new image rep for an additional scale factor
+    // is loaded and added to |image|.
+    virtual void OnExtensionIconImageChanged(IconImage* image) = 0;
+
+   protected:
+    virtual ~Observer() {}
+  };
+
+  // |context| is required by the underlying implementation to retrieve the
+  // |ImageLoader| instance associated with the given context. |ImageLoader| is
+  // used to perform the asynchronous image load work.
+  IconImage(content::BrowserContext* context,
+            const Extension* extension,
+            const ExtensionIconSet& icon_set,
+            int resource_size_in_dip,
+            const gfx::ImageSkia& default_icon,
+            Observer* observer);
+  virtual ~IconImage();
+
+  const gfx::ImageSkia& image_skia() const { return image_skia_; }
+
+ private:
+  class Source;
+
+  // Loads an image representation for the scale factor.
+  // If the representation gets loaded synchronously, it is returned by this
+  // method.
+  // If representation loading is asynchronous, an empty image
+  // representation is returned. When the representation gets loaded the
+  // observer's |OnExtensionIconImageLoaded| will be called.
+  gfx::ImageSkiaRep LoadImageForScaleFactor(ui::ScaleFactor scale_factor);
+
+  void OnImageLoaded(float scale_factor, const gfx::Image& image);
+
+  // content::NotificationObserver overrides:
+  virtual void Observe(int type,
+                       const content::NotificationSource& source,
+                       const content::NotificationDetails& details) OVERRIDE;
+
+  content::BrowserContext* browser_context_;
+  const Extension* extension_;
+  const ExtensionIconSet& icon_set_;
+  const int resource_size_in_dip_;
+
+  Observer* observer_;
+
+  Source* source_;  // Owned by ImageSkia storage.
+  gfx::ImageSkia image_skia_;
+  // The icon with whose representation |image_skia_| should be updated if
+  // its own representation load fails.
+  gfx::ImageSkia default_icon_;
+
+  content::NotificationRegistrar registrar_;
+
+  base::WeakPtrFactory<IconImage> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(IconImage);
+};
+
+}  // namespace extensions
+
+#endif  // EXTENSIONS_BROWSER_EXTENSION_ICON_IMAGE_H_