Sets the background color of shelf is opaque black when maximized (2nd)

ash/shelf/shelf_widget.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_SHELF_SHELF_WIDGET_H_
 #define ASH_SHELF_SHELF_WIDGET_H_
 
 #include "ash/ash_export.h"
 #include "ash/shelf/background_animator.h"
 #include "ash/shelf/shelf_types.h"
@@ skipping 19 matching lines @@
  public:
   ShelfWidget(
       aura::Window* shelf_container,
       aura::Window* status_container,
       internal::WorkspaceController* workspace_controller);
   virtual ~ShelfWidget();
 
   void SetAlignment(ShelfAlignment alignmnet);
   ShelfAlignment GetAlignment() const;
 
-  // Sets whether the shelf paints a background. Default is false, but is set
-  // to true if a window overlaps the shelf.
+  // Sets the shelf's background type.
   void SetPaintsBackground(
-      bool value,
+      ShelfBackgroundType background_type,
       internal::BackgroundAnimator::ChangeType change_type);
-  bool paints_background() const {
-    return background_animator_.paints_background();
-  }
+  ShelfBackgroundType GetBackgroundType() const;
 
   // Causes shelf items to be slightly dimmed (eg when a window is maximized).
   void SetDimsShelf(bool dimming);
   bool GetDimsShelf() const;
 
   internal::ShelfLayoutManager* shelf_layout_manager() {
     return shelf_layout_manager_;
   }
   Launcher* launcher() const { return launcher_.get(); }
   internal::StatusAreaWidget* status_area_widget() const {
@@ skipping 51 matching lines @@
   // during CloseChildWindows of the associated RootWindowController.
   DelegateView* delegate_view_;
   internal::BackgroundAnimator background_animator_;
   bool activating_as_fallback_;
   aura::Window* window_container_;
 };
 
 }  // namespace ash
 
 #endif  // ASH_SHELF_SHELF_WIDGET_H_