Fix the crash of DisplayErrorDialog.

ash/display/display_error_dialog_unittest.cc

Index: ash/display/display_error_dialog_unittest.cc
diff --git a/ash/display/display_error_dialog_unittest.cc b/ash/display/display_error_dialog_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..4592c86db518bdfd885641a4cf4c26a3e700dc99
--- /dev/null
+++ b/ash/display/display_error_dialog_unittest.cc
@@ -0,0 +1,55 @@
+// Copyright (c) 2013 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/test/ash_test_base.h"
+
+namespace ash {
+namespace internal {
+
+typedef test::AshTestBase DisplayErrorDialogTest;
+
+// The test cases in this file usually check if the showing dialog doesn't
+// cause any crashes, and the code doesn't cause any memory leaks.
+TEST_F(DisplayErrorDialogTest, Normal) {
+  UpdateDisplay("200x200,300x300");
+  DisplayErrorDialog::ShowDialog();
+  DisplayErrorDialog* dialog = DisplayErrorDialog::GetInstanceForTest();
+  EXPECT_TRUE(dialog);
+  EXPECT_TRUE(dialog->GetWidget()->IsVisible());

[James Cook, 2013/02/05 23:59:52]

Does this need to manually close the widget at the end of the test? 
dialog->GetWidget()->CloseNow()?

I'm not sure if AshTestBase cleans these up automatically.

[oshima, 2013/02/06 00:17:28]

If the widget's ownership is NATIVE_WIDGET_OWNS_WIDGET (which is normal),
it will. All windows are deleted upon shutdown (on both test and non test
environment), which will delete all widgets with this ownership.

+}
+
+TEST_F(DisplayErrorDialogTest, CallTwice) {
+  UpdateDisplay("200x200,300x300");
+  DisplayErrorDialog::ShowDialog();
+  DisplayErrorDialog* dialog = DisplayErrorDialog::GetInstanceForTest();
+  EXPECT_TRUE(dialog);
+  DisplayErrorDialog::ShowDialog();
+  EXPECT_EQ(dialog, DisplayErrorDialog::GetInstanceForTest());

[oshima, 2013/02/06 00:17:28]

can you test if the dialog is on the right root window?

[Jun Mukai, 2013/02/06 00:37:18]

Done.

+}
+
+TEST_F(DisplayErrorDialogTest, SingleDisplay) {
+  UpdateDisplay("200x200");
+  DisplayErrorDialog::ShowDialog();
+  DisplayErrorDialog* dialog = DisplayErrorDialog::GetInstanceForTest();
+  EXPECT_TRUE(dialog);
+  EXPECT_TRUE(dialog->GetWidget()->IsVisible());
+}
+
+TEST_F(DisplayErrorDialogTest, DisplayDisconnected) {
+  UpdateDisplay("200x200,300x300");
+  DisplayErrorDialog::ShowDialog();
+  DisplayErrorDialog* dialog = DisplayErrorDialog::GetInstanceForTest();
+  EXPECT_TRUE(dialog);
+
+  UpdateDisplay("200x200");
+  // Disconnection will close the dialog but we have to run all pending tasks
+  // to make the effect of the close.
+  RunAllPendingInMessageLoop();
+  EXPECT_FALSE(DisplayErrorDialog::GetInstanceForTest());
+}
+
+}  // namespace internal
+}  // namespace ash