2nd display should show the same background as login/lock screen:

ash/desktop_background/desktop_background_component.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_DESKTOP_BACKGROUND_DESKTOP_BACKGROUND_COMPONENT_H_
+#define ASH_DESKTOP_BACKGROUND_DESKTOP_BACKGROUND_COMPONENT_H_
+
+#include "base/memory/scoped_ptr.h"
+#include "ui/aura/window_property.h"
+#include "ui/compositor/layer.h"
+#include "ui/views/widget/widget.h"
+
+namespace ash {
+namespace internal {
+
+// This class hides difference between two possible background implementations:
+// effective Layer-based for solid color, and Widget-based for images.

[sky, 2012/07/25 20:47:36]

Change the implementation so we use a Widget for both. When you init the Widget
you can specify the the layer type in the initparams. This will simplify the
code and make it less error prone.

+class DesktopBackgroundComponent {

[sky, 2012/07/25 20:47:36]

Name this DesktopBackgroundWidgetController

[Denis Kuznetsov (DE-MUC), 2012/07/26 13:51:13]

Done.

+ public:
+  DesktopBackgroundComponent(views::Widget* widget);

[Nikita (slow), 2012/07/25 20:45:24]

explicit

[sky, 2012/07/25 20:47:36]

explicit

[Denis Kuznetsov (DE-MUC), 2012/07/26 13:51:13]

Done.

+  DesktopBackgroundComponent(ui::Layer* layer);

[Nikita (slow), 2012/07/25 20:45:24]

explicit

[Nikita (slow), 2012/07/25 20:45:24]

Please add comment that would clarify that layer ownership is transferred.

[Denis Kuznetsov (DE-MUC), 2012/07/26 13:51:13]

Done.

+
+  ~DesktopBackgroundComponent();
+
+  // Set bounds for component.
+  void SetBounds(gfx::Rect bounds);
+
+  // Move component from |src_container| in |root_window| to |dest_container|.
+  // It is required for lock screen, when we need to move background so that
+  // it hides user's windows.
+  void Reparent(aura::RootWindow* root_window,
+                int src_container,
+                int dest_container);
+
+  views::Widget* widget() { return widget_; }
+  ui::Layer* layer() { return layer_.get(); }
+
+ private:
+   views::Widget* widget_;
+   scoped_ptr<ui::Layer> layer_;
+};
+
+// Window property key, that binds instance of DesktopBackgroundComponent to
+// root windows.
+extern const aura::WindowProperty<DesktopBackgroundComponent*>* const
+    kWindowDesktopComponent;
+
+}  // namespace internal
+}  // namespace ash
+
+#endif  // ASH_DESKTOP_BACKGROUND_DESKTOP_BACKGROUND_COMPONENT_H_