Gtk3: Fix various menu colors

chrome/browser/ui/libgtkui/native_theme_gtk3.h

 // Copyright 2016 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_LIBGTKUI_NATIVE_THEME_GTK3_H_
 #define CHROME_BROWSER_UI_LIBGTKUI_NATIVE_THEME_GTK3_H_
 
 #include "base/macros.h"
 #include "ui/native_theme/native_theme_base.h"
 
@@ skipping 15 matching lines @@
   void PaintMenuItemBackground(
       SkCanvas* canvas,
       State state,
       const gfx::Rect& rect,
       const MenuItemExtraParams& menu_item) const override;
 
  private:
   NativeThemeGtk3();
   ~NativeThemeGtk3() override;
 
+  SkColor LookupGtkThemeColor(ColorId color_id) const;
+
   // Returns various widgets for theming use.
   // TODO(thomasanderson): Remove all of these.
   GtkWidget* GetWindow() const;
   GtkWidget* GetEntry() const;
   GtkWidget* GetLabel() const;
   GtkWidget* GetButton() const;
   GtkWidget* GetBlueButton() const;
   GtkWidget* GetTree() const;
   GtkWidget* GetTooltip() const;
   GtkWidget* GetMenu() const;
   GtkWidget* GetMenuItem() const;
 
   DISALLOW_COPY_AND_ASSIGN(NativeThemeGtk3);
 };
 
 }  // namespace libgtkui
 
 #endif  // CHROME_BROWSER_UI_LIBGTKUI_NATIVE_THEME_GTK3_H_