Set toolbar padding to something appropriate for Metro icons.

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.
+  LAYOUT_ASH,
+
+  // The typical layout for e.g. Windows, Mac and Linux.
+  LAYOUT_DESKTOP,
+
+  // Layout optimized for Windows 8 in Metro mode.
+  LAYOUT_METRO,
+};
+
+// 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 const DisplayLayout GetDisplayLayout();
+
+}  // namespace ui
+
+#endif  // UI_BASE_LAYOUT_H_