Implements the dialog view for logout button tray in public sessions.

ash/system/logout_button/logout_button_tray.cc

Index: ash/system/logout_button/logout_button_tray.cc
diff --git a/ash/system/logout_button/logout_button_tray.cc b/ash/system/logout_button/logout_button_tray.cc
index c06073040c5c26822b641ecb479f29c65cae088f..4d62ae48cf83d2b078915060986e813198149af2 100644
--- a/ash/system/logout_button/logout_button_tray.cc
+++ b/ash/system/logout_button/logout_button_tray.cc
@@ -6,12 +6,14 @@
 
 #include "ash/shelf/shelf_types.h"
 #include "ash/shell.h"
+#include "ash/system/logout_button/logout_confirmation_dialog_view.h"
 #include "ash/system/status_area_widget.h"
 #include "ash/system/tray/system_tray_delegate.h"
 #include "ash/system/tray/system_tray_notifier.h"
 #include "ash/system/tray/tray_constants.h"
 #include "ash/system/tray/tray_utils.h"
 #include "base/logging.h"
+#include "base/message_loop/message_loop.h"
 #include "grit/ash_resources.h"
 #include "third_party/skia/include/core/SkColor.h"
 #include "ui/events/event.h"
@@ -96,7 +98,6 @@ LogoutButton::~LogoutButton() {
 
 LogoutButtonTray::LogoutButtonTray(StatusAreaWidget* status_area_widget)
     : TrayBackgroundView(status_area_widget),
-      button_(NULL),
       login_status_(user::LOGGED_IN_NONE),
       show_logout_button_in_tray_(false) {
   button_ = new LogoutButton(this);
@@ -106,10 +107,27 @@ LogoutButtonTray::LogoutButtonTray(StatusAreaWidget* status_area_widget)
 }
 
 LogoutButtonTray::~LogoutButtonTray() {
+  EnsureConfirmationDialogIsClosed();
   Shell::GetInstance()->system_tray_notifier()->
       RemoveLogoutButtonObserver(this);
 }
 
+void LogoutButtonTray::EnsureConfirmationDialogIsShowing() {
+  if (!confirmation_dialog_) {
+    confirmation_dialog_.reset(new LogoutConfirmationDialogView(this));
+    confirmation_dialog_->Show(dialog_duration_);
+  }
+}
+
+void LogoutButtonTray::EnsureConfirmationDialogIsClosed() {
+  if (confirmation_dialog_) {
+    confirmation_dialog_->GetWidget()->Close();

[bartfab (slow), 2013/11/20 18:00:44]

Are you sure that closing the widget will not destroy the delegate for you?

Looking at the code,
Widget::OnNativeWidgetDestroyed()
calls
DialogDelegateView::DeleteDelegate
which destroys the delegate. Is it correct to explicitly destroy the delegate?
Will this not produce a double-free?

+    LogoutConfirmationDialogView* dialog = UnbindWithConfirmationDialog();
+    if (dialog)
+      base::MessageLoop::current()->DeleteSoon(FROM_HERE, dialog);
+  }
+}
+
 void LogoutButtonTray::SetShelfAlignment(ShelfAlignment alignment) {
   TrayBackgroundView::SetShelfAlignment(alignment);
   tray_container()->set_border(NULL);
@@ -132,10 +150,20 @@ void LogoutButtonTray::OnShowLogoutButtonInTrayChanged(bool show) {
   UpdateVisibility();
 }
 
+void LogoutButtonTray::OnLogoutDialogDurationChanged(base::TimeDelta duration) {
+  dialog_duration_ = duration;
+  if (confirmation_dialog_)
+    confirmation_dialog_->UpdateDialogDuration(dialog_duration_);
+}
+
 void LogoutButtonTray::ButtonPressed(views::Button* sender,
                                      const ui::Event& event) {
   DCHECK_EQ(sender, button_);
-  Shell::GetInstance()->system_tray_delegate()->SignOut();
+  // Sign out immediately if kLogoutDialogDurationMs is non-positive.
+  if (dialog_duration_ <= base::TimeDelta::FromSeconds(0))
+    Shell::GetInstance()->system_tray_delegate()->SignOut();
+  else
+    EnsureConfirmationDialogIsShowing();
 }
 
 void LogoutButtonTray::UpdateAfterLoginStatusChange(
@@ -148,10 +176,25 @@ void LogoutButtonTray::UpdateAfterLoginStatusChange(
   UpdateVisibility();
 }
 
+LogoutConfirmationDialogView* LogoutButtonTray::UnbindWithConfirmationDialog() {
+  // Use atomic operation to nullify two pointers. This function can be called
+  // from both LogoutButtonTray and LogoutConfirmationDialogView, and the
+  // destroy order of these two class doesn't matter now. Be careful this
+  // function is not thread safe, and the dialog might not be destroyed yet.
+  if (confirmation_dialog_) {
+    LogoutConfirmationDialogView *dialog = confirmation_dialog_.release();
+    dialog->ClearOwner();
+    return dialog;
+  }
+  return NULL;
+}
+
 void LogoutButtonTray::UpdateVisibility() {
   SetVisible(show_logout_button_in_tray_ &&
              login_status_ != user::LOGGED_IN_NONE &&
              login_status_ != user::LOGGED_IN_LOCKED);
+  if (!show_logout_button_in_tray_)
+    EnsureConfirmationDialogIsClosed();
 }
 
 }  // namespace internal