Allow dynamic enabling/disabling of unified desktop

ash/shelf/shelf_layout_manager_unittest.cc

 // 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.
 
 #include "ash/shelf/shelf_layout_manager.h"
 
 #include "ash/accelerators/accelerator_controller.h"
 #include "ash/accelerators/accelerator_table.h"
 #include "ash/ash_switches.h"
 #include "ash/display/display_manager.h"
@@ skipping 2331 matching lines @@
 
   // Deleting a focused maximized window will switch focus to |window2|. This
   // would normally cause the ShelfLayoutManager to update its state. However
   // during shutdown we want to handle this without crashing.
   delete window1;
 }
 
 TEST_F(ShelfLayoutManagerTest, ShelfLayoutInUnifiedDesktop) {
   if (!SupportsMultipleDisplays())
     return;
-  test::DisplayManagerTestApi::EnableUnifiedDesktopForTest();
+  Shell::GetInstance()->display_manager()->SetUnifiedDesktopEnabled(true);
 
   UpdateDisplay("500x500, 500x500");
 
   StatusAreaWidget* status_area_widget =
       Shell::GetPrimaryRootWindowController()->shelf()->status_area_widget();
   EXPECT_TRUE(status_area_widget->IsVisible());
   // Shelf should be in the first display's area.
   EXPECT_EQ("348,453 152x47",
             status_area_widget->GetWindowBoundsInScreen().ToString());
 }
 
 }  // namespace ash