Add a new GetSystemColor method to native theme.

ui/gfx/native_theme_base.h

 // Copyright (c) 2011 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_NATIVE_THEME_BASE_H_
 #define UI_GFX_NATIVE_THEME_BASE_H_
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "skia/ext/platform_canvas.h"
 #include "ui/gfx/native_theme.h"
 
 namespace gfx {
 class Rect;
 class Size;
 
 // Theme support for non-Windows toolkits.
 class NativeThemeBase : public NativeTheme {
  public:
   // NativeTheme implementation:
   virtual gfx::Size GetPartSize(Part part,
                                 State state,
                                 const ExtraParams& extra) const OVERRIDE;
   virtual void Paint(SkCanvas* canvas,
                      Part part,
                      State state,
                      const gfx::Rect& rect,
                      const ExtraParams& extra) const OVERRIDE;
 
+  // This implementation returns hardcoded default colors.
+  virtual SkColor GetSystemColor(ColorId color_id) const OVERRIDE;
+
  protected:
   NativeThemeBase();
   virtual ~NativeThemeBase();
 
   // Draw the arrow. Used by scrollbar and inner spin button.
   virtual void PaintArrowButton(
       SkCanvas* gc,
       const gfx::Rect& rect,
       Part direction,
       State state) const;
@@ skipping 117 matching lines @@
 
   static unsigned int scrollbar_width_;
   static unsigned int button_length_;
 
   DISALLOW_COPY_AND_ASSIGN(NativeThemeBase);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_NATIVE_THEME_BASE_H_