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..76752b79324e551e21eb5ab1c4efa381904fce33 100644
--- a/ash/system/logout_button/logout_button_tray.cc
+++ b/ash/system/logout_button/logout_button_tray.cc
@@ -24,7 +24,6 @@
 #include "ui/views/painter.h"
 
 namespace ash {
-
 namespace internal {
 
 namespace {
@@ -98,16 +97,43 @@ LogoutButtonTray::LogoutButtonTray(StatusAreaWidget* status_area_widget)
     : TrayBackgroundView(status_area_widget),
       button_(NULL),
       login_status_(user::LOGGED_IN_NONE),
-      show_logout_button_in_tray_(false) {
+      show_logout_button_in_tray_(false),
+      confirmation_dialog_(NULL),
+      confirmation_delegate_(new LogoutConfirmationDialogView::Delegate) {
   button_ = new LogoutButton(this);
   tray_container()->AddChildView(button_);
   tray_container()->set_border(NULL);
-  Shell::GetInstance()->system_tray_notifier()->AddLogoutButtonObserver(this);
+  // The Shell may not exist in some unit tests.
+  if (Shell::HasInstance()) {
+    Shell::GetInstance()->system_tray_notifier()->
+        AddLogoutButtonObserver(this);
+  }
 }
 
 LogoutButtonTray::~LogoutButtonTray() {
-  Shell::GetInstance()->system_tray_notifier()->
-      RemoveLogoutButtonObserver(this);
+  EnsureConfirmationDialogIsClosed();
+  // The Shell may not exist in some unit tests.
+  if (Shell::HasInstance()) {
+    Shell::GetInstance()->system_tray_notifier()->
+        RemoveLogoutButtonObserver(this);
+  }
+}
+
+bool LogoutButtonTray::IsConfirmationDialogShowing() const {
+  return confirmation_dialog_;
+}
+
+void LogoutButtonTray::EnsureConfirmationDialogIsShowing() {
+  if (!confirmation_dialog_) {
+    confirmation_dialog_ = new LogoutConfirmationDialogView(
+        this, confirmation_delegate_.get());
+    confirmation_dialog_->Show(dialog_duration_);
+  }
+}
+
+void LogoutButtonTray::EnsureConfirmationDialogIsClosed() {
+  if (confirmation_dialog_)
+    confirmation_dialog_->Close();
 }
 
 void LogoutButtonTray::SetShelfAlignment(ShelfAlignment alignment) {
@@ -132,10 +158,20 @@ 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 |dialog_duration_| is non-positive.
+  if (dialog_duration_ <= base::TimeDelta())
+    confirmation_delegate_->LogoutCurrentUser();
+  else
+    EnsureConfirmationDialogIsShowing();
 }
 
 void LogoutButtonTray::UpdateAfterLoginStatusChange(
@@ -148,10 +184,21 @@ void LogoutButtonTray::UpdateAfterLoginStatusChange(
   UpdateVisibility();
 }
 
+void LogoutButtonTray::ReleaseConfirmationDialog() {
+  confirmation_dialog_ = NULL;
+}
+
+void LogoutButtonTray::SetDelegateForTest(
+    scoped_ptr<LogoutConfirmationDialogView::Delegate> delegate) {
+  confirmation_delegate_ = delegate.Pass();
+}
+
 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