Revert 149869 because it broke ash_unittests on win_aura and linux_chromeos.

ash/root_window_controller.cc

Index: ash/root_window_controller.cc
===================================================================
--- ash/root_window_controller.cc	(revision 149877)
+++ ash/root_window_controller.cc	(working copy)
@@ -6,7 +6,6 @@
 
 #include <vector>
 
-#include "ash/desktop_background/desktop_background_widget_controller.h"
 #include "ash/display/display_controller.h"
 #include "ash/shell.h"
 #include "ash/shell_factory.h"
@@ -170,13 +169,6 @@
       non_lock_screen_containers);
   SetUsesScreenCoordinates(input_method_container);
 
-  aura::Window* lock_background_containers = CreateContainer(
-      internal::kShellWindowId_LockScreenBackgroundContainer,
-      "LockScreenBackgroundContainer",
-      lock_screen_containers);
-
-  SetChildWindowVisibilityChangesAnimated(lock_background_containers);
-
   // TODO(beng): Figure out if we can make this use
   // SystemModalContainerEventFilter instead of stops_event_propagation.
   aura::Window* lock_container = CreateContainer(
@@ -286,9 +278,7 @@
 
 void RootWindowController::CloseChildWindows() {
   // Close background widget first as it depends on tooltip.
-  root_window_->SetProperty(kWindowDesktopComponent,
-      static_cast<DesktopBackgroundWidgetController*>(NULL));
-
+  root_window_layout_->SetBackgroundWidget(NULL);
   workspace_controller_.reset();
   aura::client::SetTooltipClient(root_window_.get(), NULL);