Align layers for ARC notification surface to pixels

ash/wm/window_util.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 ASH_WM_WINDOW_UTIL_H_
 #define ASH_WM_WINDOW_UTIL_H_
 
 #include "ash/ash_export.h"
 #include "base/compiler_specific.h"
 #include "ui/base/ui_base_types.h"
@@ skipping 29 matching lines @@
 
 // Pins the window on top of other windows.
 ASH_EXPORT void PinWindow(aura::Window* window, bool trusted);
 
 // Moves |window| to the root window where the |event| occured if it is not
 // already in the same root window. Returns true if |window| was moved.
 ASH_EXPORT bool MoveWindowToEventRoot(aura::Window* window,
                                       const ui::Event& event);
 
 // Snap the window's layer to physical pixel boundary.
-void SnapWindowToPixelBoundary(aura::Window* window);
+ASH_EXPORT void SnapWindowToPixelBoundary(aura::Window* window);
 
 // Mark the container window so that InstallSnapLayoutManagerToContainers
 // installs the SnapToPixelLayoutManager.
 ASH_EXPORT void SetSnapsChildrenToPhysicalPixelBoundary(
     aura::Window* container);
 
 }  // namespace wm
 }  // namespace ash
 
 #endif  // ASH_WM_WINDOW_UTIL_H_