Select theme resources from ResourceBundle at requested scale factor.

ui/base/layout.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_BASE_LAYOUT_H_
 #define UI_BASE_LAYOUT_H_
 #pragma once
 
 #include "ui/base/ui_export.h"
 
 namespace ui {
 
 enum DisplayLayout {
   // Layout optimized for ASH.  This enum value should go away as soon as
   // LAYOUT_DESKTOP and LAYOUT_ASH are the same.
   LAYOUT_ASH,
 
   // The typical layout for e.g. Windows, Mac and Linux.
   LAYOUT_DESKTOP,
 
   // Layout optimized for touch.  Used e.g. for Windows 8 Metro mode.
   LAYOUT_TOUCH,
 };
 
 // Returns the display layout that should be used.  This could be used
 // e.g. to tweak hard-coded padding that's layout specific, or choose
 // the .pak file of theme resources to load.
 UI_EXPORT DisplayLayout GetDisplayLayout();
 
+enum ScaleFactor {
+  SCALE_FACTOR_100P,
+
+  // The scale factor used for unscaled binary data, the 1x (default) scale
+  // factor data packs.
+  SCALE_FACTOR_NONE = SCALE_FACTOR_100P,
+
+  SCALE_FACTOR_200P,
+};
+
 }  // namespace ui
 
 #endif  // UI_BASE_LAYOUT_H_