Remove root_window_ member from DesktopBackgroundController.

ash/desktop_background/desktop_background_controller.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/desktop_background/desktop_background_controller.h"
 
 #include "ash/desktop_background/desktop_background_view.h"
 #include "ash/shell.h"
 #include "ash/shell_factory.h"
 #include "ash/shell_window_ids.h"
@@ skipping 67 matching lines @@
 
   base::CancellationFlag cancel_flag_;
 
   const gfx::ImageSkia* wallpaper_;
   WallpaperLayout layout_;
   int index_;
 
   DISALLOW_COPY_AND_ASSIGN(WallpaperOperation);
 };
 
-DesktopBackgroundController::DesktopBackgroundController(
-    aura::RootWindow* root_window)
-    : root_window_(root_window),
-      desktop_background_mode_(BACKGROUND_IMAGE),
+DesktopBackgroundController::DesktopBackgroundController()
+    : desktop_background_mode_(BACKGROUND_IMAGE),
       previous_index_(-1),
       weak_ptr_factory_(ALLOW_THIS_IN_INITIALIZER_LIST(this)) {
-  DCHECK(root_window_);
 }
 
 DesktopBackgroundController::~DesktopBackgroundController() {
   CancelPendingWallpaperOperation();
 }
 
 void DesktopBackgroundController::SetDefaultWallpaper(int index) {
   // We should not change background when index is invalid. For instance, at
   // login screen or stub_user login.
   if (index == ash::GetInvalidWallpaperIndex()) {
@@ skipping 15 matching lines @@
       base::Bind(&WallpaperOperation::Run, wallpaper_op_),
       base::Bind(&DesktopBackgroundController::OnWallpaperLoadCompleted,
                  weak_ptr_factory_.GetWeakPtr(),
                  wallpaper_op_),
       true /* task_is_slow */);
 }
 
 void DesktopBackgroundController::SetCustomWallpaper(
     const gfx::ImageSkia& wallpaper,
     WallpaperLayout layout) {
-  GetRootWindowLayoutManager(root_window_)->SetBackgroundLayer(NULL);
-  internal::CreateDesktopBackground(wallpaper, layout, root_window_);
+  aura::RootWindow* root_window = Shell::GetPrimaryRootWindow();
+  GetRootWindowLayoutManager(root_window)->SetBackgroundLayer(NULL);
+  internal::CreateDesktopBackground(wallpaper, layout, root_window);
   desktop_background_mode_ = BACKGROUND_IMAGE;
 }
 
 void DesktopBackgroundController::CancelPendingWallpaperOperation() {
   // Set canceled flag of previous request to skip unneeded loading.
   if (wallpaper_op_.get())
     wallpaper_op_->Cancel();
 
   // Cancel reply callback for previous request.
   weak_ptr_factory_.InvalidateWeakPtrs();
 }
 
 void DesktopBackgroundController::SetDesktopBackgroundSolidColorMode(
     SkColor color) {
   // Set a solid black background.
   // TODO(derat): Remove this in favor of having the compositor only clear the
   // viewport when there are regions not covered by a layer:
   // http://crbug.com/113445
   ui::Layer* background_layer = new ui::Layer(ui::LAYER_SOLID_COLOR);
   background_layer->SetColor(color);
-  root_window_->GetChildById(
+  aura::RootWindow* root_window = Shell::GetPrimaryRootWindow();
+  Shell::GetContainer(
+      root_window,
       internal::kShellWindowId_DesktopBackgroundContainer)->
       layer()->Add(background_layer);
-  GetRootWindowLayoutManager(root_window_)->SetBackgroundLayer(
+  GetRootWindowLayoutManager(root_window)->SetBackgroundLayer(
       background_layer);
-  GetRootWindowLayoutManager(root_window_)->SetBackgroundWidget(NULL);
+  GetRootWindowLayoutManager(root_window)->SetBackgroundWidget(NULL);
   desktop_background_mode_ = BACKGROUND_SOLID_COLOR;
 }
 
 void DesktopBackgroundController::SetDesktopBackgroundImageMode(
     scoped_refptr<WallpaperOperation> wo) {
-  GetRootWindowLayoutManager(root_window_)->SetBackgroundLayer(NULL);
-  if(wo->wallpaper()) {
+  aura::RootWindow* root_window = Shell::GetPrimaryRootWindow();
+  GetRootWindowLayoutManager(root_window)->SetBackgroundLayer(NULL);
+  if (wo->wallpaper()) {
     internal::CreateDesktopBackground(
-        *wo->wallpaper(), wo->wallpaper_layout(), root_window_);
+        *wo->wallpaper(), wo->wallpaper_layout(), root_window);
     desktop_background_mode_ = BACKGROUND_IMAGE;
   }
 }
 
 void DesktopBackgroundController::OnWallpaperLoadCompleted(
     scoped_refptr<WallpaperOperation> wo) {
   SetDesktopBackgroundImageMode(wo);
   previous_index_ = wo->index();
 
   DCHECK(wo.get() == wallpaper_op_.get());
   wallpaper_op_ = NULL;
 }
 
 void DesktopBackgroundController::CreateEmptyWallpaper() {
   gfx::ImageSkia dummy;
-  internal::CreateDesktopBackground(dummy, CENTER, root_window_);
+  internal::CreateDesktopBackground(
+      dummy, CENTER, Shell::GetPrimaryRootWindow());
   desktop_background_mode_ = BACKGROUND_IMAGE;
 }
 
 }  // namespace ash