Do not use assets for Ash window control button backgrounds

chrome/browser/ui/views/frame/browser_header_painter_ash.h

 // 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 CHROME_BROWSER_UI_VIEWS_FRAME_BROWSER_HEADER_PAINTER_ASH_H_
 #define CHROME_BROWSER_UI_VIEWS_FRAME_BROWSER_HEADER_PAINTER_ASH_H_
 
 #include "ash/frame/header_painter.h"
 #include "base/compiler_specific.h"  // override
 #include "base/macros.h"
@@ skipping 63 matching lines @@
   // for tabbed browser windows.
   void GetFrameImagesForTabbedBrowser(
       Mode mode,
       gfx::ImageSkia* frame_image,
       gfx::ImageSkia* frame_overlay_image) const;
 
   // Returns the frame image which should be used to paint the header for popup
   // browser windows and for hosted app windows which show the toolbar.
   gfx::ImageSkia GetFrameImageForNonTabbedBrowser(Mode mode) const;
 
-  // Updates the images used for the minimize, restore and close buttons.
-  void UpdateCaptionButtonImages();
+  // Updates the size and icons used for the minimize, restore, and close
+  // buttons.
+  void UpdateCaptionButtons();
 
   // Returns bounds of the region in |view_| which is painted with the header
   // images. The region is assumed to start at the top left corner of |view_|
   // and to have the same width as |view_|.
   gfx::Rect GetPaintedBounds() const;
 
   // Returns the bounds for the title.
   gfx::Rect GetTitleBounds() const;
 
   views::Widget* frame_;
@@ skipping 17 matching lines @@
 
   // Whether the header should be painted as active.
   Mode mode_;
 
   scoped_ptr<gfx::SlideAnimation> activation_animation_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowserHeaderPainterAsh);
 };
 
 #endif  // CHROME_BROWSER_UI_VIEWS_FRAME_BROWSER_HEADER_PAINTER_ASH_H_