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

ash/system/tray/tray_background_view.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/system/tray/tray_background_view.h"
 
 #include "ash/ash_switches.h"
 #include "ash/root_window_controller.h"
 #include "ash/screen_ash.h"
 #include "ash/shelf/shelf_layout_manager.h"
@@ skipping 555 matching lines @@
           kPaddingFromBottomOfScreenVerticalAlignment;
       if (anchor_alignment == TrayBubbleView::ANCHOR_ALIGNMENT_LEFT)
         rect.Inset(vertical_alignment, 0, 0, horizontal_alignment);
       else if (anchor_alignment == TrayBubbleView::ANCHOR_ALIGNMENT_RIGHT)
         rect.Inset(0, 0, vertical_alignment, horizontal_alignment);
     }
   }
 
   // TODO(jennyz): May need to add left/right alignment in the following code.
   if (rect.IsEmpty()) {
-    aura::RootWindow* target_root = anchor_widget ?
+    aura::Window* target_root = anchor_widget ?
         anchor_widget->GetNativeView()->GetRootWindow() :
         Shell::GetPrimaryRootWindow();
     rect = target_root->bounds();
     rect = gfx::Rect(
         base::i18n::IsRTL() ? kPaddingFromRightEdgeOfScreenBottomAlignment :
         rect.width() - kPaddingFromRightEdgeOfScreenBottomAlignment,
         rect.height() - kPaddingFromBottomOfScreenBottomAlignment,
         0, 0);
     rect = ScreenAsh::ConvertRectToScreen(target_root, rect);
   }
@@ skipping 28 matching lines @@
   else
     background_->set_alpha(kTrayBackgroundAlpha);
   SchedulePaint();
 }
 
 void TrayBackgroundView::UpdateBubbleViewArrow(
     views::TrayBubbleView* bubble_view) {
   if (switches::UseAlternateShelfLayout())
     return;
 
-  aura::RootWindow* root_window =
+  aura::Window* root_window =
       bubble_view->GetWidget()->GetNativeView()->GetRootWindow();
   ash::internal::ShelfLayoutManager* shelf =
       ShelfLayoutManager::ForLauncher(root_window);
   bubble_view->SetArrowPaintType(
       (shelf && shelf->IsVisible()) ?
       views::BubbleBorder::PAINT_NORMAL :
       views::BubbleBorder::PAINT_TRANSPARENT);
 }
 
 }  // namespace internal
 }  // namespace ash