Reland - cros: Add CHECK for screen unlock problem

ash/desktop_background/desktop_background_widget_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_widget_controller.h"
 
 #include "ui/aura/root_window.h"
 #include "ui/views/widget/widget.h"
 
 DECLARE_WINDOW_PROPERTY_TYPE(ash::internal::DesktopBackgroundWidgetController*);
@@ skipping 31 matching lines @@
   widget_ = NULL;
 }
 
 void DesktopBackgroundWidgetController::SetBounds(gfx::Rect bounds) {
   if (widget_)
     widget_->SetBounds(bounds);
   else if (layer_.get())
     layer_->SetBounds(bounds);
 }
 
-void DesktopBackgroundWidgetController::Reparent(aura::RootWindow* root_window,
+bool DesktopBackgroundWidgetController::Reparent(aura::RootWindow* root_window,
                                                  int src_container,
                                                  int dest_container) {
   if (widget_) {
     views::Widget::ReparentNativeView(widget_->GetNativeView(),
         root_window->GetChildById(dest_container));
-  } else if (layer_.get()) {
+    return true;
+  }
+  if (layer_.get()) {
     ui::Layer* layer = layer_.get();
     root_window->GetChildById(src_container)->layer()->Remove(layer);
     root_window->GetChildById(dest_container)->layer()->Add(layer);
+    return true;
   }
+  // Nothing to reparent.
+  return false;
 }
 
 ComponentWrapper::ComponentWrapper(
     DesktopBackgroundWidgetController* component) {
   component_.reset(component);
 }
 
 ComponentWrapper::~ComponentWrapper() {
 }
 
 DesktopBackgroundWidgetController* ComponentWrapper::GetComponent(
     bool pass_ownership) {
   if (pass_ownership)
     return component_.release();
   return component_.get();
 }
 
 }  // namespace internal
 }  // namespace ash