Fix the crash of DisplayErrorDialog.

ash/display/display_error_dialog.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/display/display_error_dialog.h"
 
 #include "ash/screen_ash.h"
 #include "ash/shell.h"
 #include "grit/ash_strings.h"
+#include "ui/aura/root_window.h"
 #include "ui/aura/window.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/base/ui_base_types.h"
 #include "ui/gfx/display.h"
 #include "ui/gfx/screen.h"
 #include "ui/views/border.h"
 #include "ui/views/controls/label.h"
 #include "ui/views/widget/widget.h"
 
 namespace ash {
@@ skipping 12 matching lines @@
 
 // static
 void  DisplayErrorDialog::ShowDialog() {
   if (g_instance) {
     DCHECK(g_instance->GetWidget());
     g_instance->GetWidget()->StackAtTop();
     g_instance->GetWidget()->Activate();
     return;
   }
 
-  const gfx::Display& secondary_display = ash::ScreenAsh::GetSecondaryDisplay();
+  gfx::Screen* screen = Shell::GetScreen();
+  const gfx::Display& target_display =
+      (screen->GetNumDisplays() > 1) ?
+      ScreenAsh::GetSecondaryDisplay() : screen->GetPrimaryDisplay();
 
   g_instance = new DisplayErrorDialog();
   views::Widget* widget = new views::Widget;
   views::Widget::InitParams params(views::Widget::InitParams::TYPE_WINDOW);
   params.delegate = g_instance;
-  // Makes |widget| belong to the secondary display.  Size and location are
+  // Makes |widget| belong to the target display.  Size and location are
   // fixed by CenterWindow() below.
-  params.bounds = secondary_display.bounds();
+  params.bounds = target_display.bounds();
+  DisplayController* display_controller =
+      Shell::GetInstance()->display_controller();
+  params.context =
+      display_controller->GetRootWindowForDisplayId(target_display.id());
   params.keep_on_top = true;
   widget->Init(params);
 
   widget->GetNativeView()->SetName("DisplayErrorDialog");
   widget->CenterWindow(widget->GetRootView()->GetPreferredSize());
   widget->Show();
 }
 
 DisplayErrorDialog::DisplayErrorDialog() {
   Shell::GetInstance()->display_controller()->AddObserver(this);
@@ skipping 25 matching lines @@
 }
 
 gfx::Size DisplayErrorDialog::GetPreferredSize() {
   return label_->GetPreferredSize();
 }
 
 void DisplayErrorDialog::OnDisplayConfigurationChanging() {
   GetWidget()->Close();
 }
 
+// static
+DisplayErrorDialog* DisplayErrorDialog::GetInstanceForTest() {
+  return g_instance;
+}
+
 }  // namespace internal
 }  // namespace ash