Adds DisplayErrorDialog to show the error message of the failure of mirroring to the users.

ash/display/display_error_dialog.cc

Index: ash/display/display_error_dialog.cc
diff --git a/ash/display/display_error_dialog.cc b/ash/display/display_error_dialog.cc
new file mode 100644
index 0000000000000000000000000000000000000000..4933cd8f068c3a77f9416f9c34eadc625a1cbead
--- /dev/null
+++ b/ash/display/display_error_dialog.cc
@@ -0,0 +1,101 @@
+// 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/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 {
+namespace internal {
+namespace {
+
+// The width of the area to show the error message.
+const int kDialogMessageWidthPixel = 300;
+
+// The margin width from the error message to the edge of the dialog.
+const int kDialogMessageMarginWidthPixel = 5;
+
+DisplayErrorDialog* g_instance = NULL;
+
+}  // namespace
+
+// 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();
+
+  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
+  // fixed by CenterWindow() below.
+  params.bounds = secondary_display.bounds();
+  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);
+  label_ = new views::Label(
+      l10n_util::GetStringUTF16(IDS_ASH_DISPLAY_FAILURE_ON_MIRRORING));
+  AddChildView(label_);
+
+  label_->SetMultiLine(true);
+  label_->SetHorizontalAlignment(views::Label::ALIGN_LEFT);
+  label_->set_border(views::Border::CreateEmptyBorder(
+      kDialogMessageMarginWidthPixel,
+      kDialogMessageMarginWidthPixel,
+      kDialogMessageMarginWidthPixel,
+      kDialogMessageMarginWidthPixel));
+  label_->SizeToFit(kDialogMessageWidthPixel);
+}
+
+DisplayErrorDialog::~DisplayErrorDialog() {
+  Shell::GetInstance()->display_controller()->RemoveObserver(this);
+  g_instance = NULL;
+}
+
+int DisplayErrorDialog::GetDialogButtons() const {
+  return ui::DIALOG_BUTTON_OK;
+}
+
+ui::ModalType DisplayErrorDialog::GetModalType() const {
+  return ui::MODAL_TYPE_NONE;
+}
+
+views::View* DisplayErrorDialog::GetContentsView() {
+  return this;
+}
+
+gfx::Size DisplayErrorDialog::GetPreferredSize() {
+  return label_->GetPreferredSize();
+}
+
+void DisplayErrorDialog::OnDisplayConfigurationChanging() {
+  GetWidget()->Close();
+}
+
+}  // namespace internal
+}  // namespace ash