Gtk3: Add foreign-drawing for menus

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"
 
 typedef struct _GtkWidget GtkWidget;
 
 namespace libgtkui {
 
 // A version of NativeTheme that uses GTK3-rendered widgets.
 class NativeThemeGtk3 : public ui::NativeThemeBase {
  public:
   static NativeThemeGtk3* instance();
 
   // Overridden from ui::NativeThemeBase:
   SkColor GetSystemColor(ColorId color_id) const override;
+  void PaintMenuPopupBackground(
+      SkCanvas* canvas,
+      const gfx::Size& size,
+      const MenuBackgroundExtraParams& menu_background) const override;
+  void PaintMenuItemBackground(
+      SkCanvas* canvas,
+      State state,
+      const gfx::Rect& rect,
+      const MenuItemExtraParams& menu_item) const override;
 
  private:
   NativeThemeGtk3();
   ~NativeThemeGtk3() override;
 
   // 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_