Loading/Creating images for mutiple scale factors on the fly

ui/gfx/image/image_skia_source.h

+// Copyright (c) 2012 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 UI_GFX_IMAGE_IMAGE_SKIA_SOURCE_H_
+#define UI_GFX_IMAGE_IMAGE_SKIA_SOURCE_H_
+#pragma once
+
+#include "ui/base/layout.h"
+
+namespace gfx {
+
+class ImageSkiaRep;
+
+class ImageSkiaSource {
+ public:
+  virtual ~ImageSkiaSource() {}
+
+  // Returns the ImageSkiaRep for the given |scale_factor|.
+  virtual gfx::ImageSkiaRep GetImageForScale(ui::ScaleFactor scale_factor) = 0;

[sky, 2012/07/16 16:44:31]

This should document the source shouldn't cache the imagerep since ImageSkia
caches the returned value.

+};
+
+}  // namespace gfx
+
+#endif  // UI_GFX_IMAGE_IMAGE_SKIA_SOURCE_H_