Make GetRootWindow() return a Window instead of a RootWindow.

ash/wm/panels/panel_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/wm/panels/panel_layout_manager.h"
 
 #include "ash/ash_switches.h"
 #include "ash/launcher/launcher.h"
 #include "ash/launcher/launcher_button.h"
 #include "ash/launcher/launcher_model.h"
@@ skipping 218 matching lines @@
     int index = model->ItemIndexByID(launcher_delegate->GetIDByWindow(window));
     gfx::Rect bounds = test_api.GetButton(index)->GetBoundsInScreen();
 
     aura::test::EventGenerator& event_generator = GetEventGenerator();
     event_generator.MoveMouseTo(bounds.CenterPoint());
     event_generator.ClickLeftButton();
 
     test_api.RunMessageLoopUntilAnimationsDone();
   }
 
-  void SetAlignment(aura::RootWindow* root_window, ShelfAlignment alignment) {
+  void SetAlignment(aura::Window* root_window, ShelfAlignment alignment) {
     ash::Shell* shell = ash::Shell::GetInstance();
     shell->SetShelfAlignment(alignment, root_window);
   }
 
-  ShelfAlignment GetAlignment(aura::RootWindow* root_window) {
+  ShelfAlignment GetAlignment(aura::Window* root_window) {
     ash::Shell* shell = ash::Shell::GetInstance();
     return shell->GetShelfAlignment(root_window);
   }
 
   void SetShelfAutoHideBehavior(aura::Window* window,
                                 ShelfAutoHideBehavior behavior) {
     internal::ShelfLayoutManager* shelf =
         RootWindowController::ForWindow(window)->shelf()->
         shelf_layout_manager();
     shelf->SetAutoHideBehavior(behavior);
@@ skipping 523 matching lines @@
   EXPECT_TRUE(w1->IsVisible());
   EXPECT_FALSE(w2->IsVisible());
   EXPECT_TRUE(w3->IsVisible());
 }
 
 INSTANTIATE_TEST_CASE_P(LtrRtl, PanelLayoutManagerTextDirectionTest,
                         testing::Bool());
 
 }  // namespace internal
 }  // namespace ash