Rewrite scoped_ptr<T>(NULL) to use the default ctor in ash/.

ash/root_window_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/root_window_controller.h"
 
 #include <vector>
 
 #include "ash/ash_constants.h"
 #include "ash/ash_switches.h"
@@ skipping 148 matching lines @@
   container->SetProperty(internal::kUsesScreenCoordinatesKey, true);
 }
 
 }  // namespace
 
 namespace internal {
 
 RootWindowController::RootWindowController(aura::RootWindow* root_window)
     : root_window_(root_window),
       root_window_layout_(NULL),
-      shelf_(NULL),
       panel_layout_manager_(NULL),
       touch_observer_hud_(NULL) {
   SetRootWindowController(root_window, this);
   screen_dimmer_.reset(new ScreenDimmer(root_window));
 
   stacking_controller_.reset(new ash::StackingController);
   aura::client::SetStackingClient(root_window, stacking_controller_.get());
 }
 
 RootWindowController::~RootWindowController() {
@@ skipping 447 matching lines @@
       "OverlayContainer",
       lock_screen_related_containers);
   SetUsesScreenCoordinates(overlay_container);
 
   CreateContainer(kShellWindowId_PowerButtonAnimationContainer,
                   "PowerButtonAnimationContainer", root_window) ;
 }
 
 }  // namespace internal
 }  // namespace ash