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

ash/system/logout_button/logout_button_tray.h

Index: ash/system/logout_button/logout_button_tray.h
diff --git a/ash/system/logout_button/logout_button_tray.h b/ash/system/logout_button/logout_button_tray.h
index 5683e5e2654c13f52e1d2e9efe0a9403e91b9cf2..5755835b68bd7ea676a8c433ccaf11013f7fc1f0 100644
--- a/ash/system/logout_button/logout_button_tray.h
+++ b/ash/system/logout_button/logout_button_tray.h
@@ -5,11 +5,15 @@
 #ifndef ASH_SYSTEM_LOGOUT_BUTTON_LOGOUT_BUTTON_TRAY_H_
 #define ASH_SYSTEM_LOGOUT_BUTTON_LOGOUT_BUTTON_TRAY_H_
 
+#include "ash/ash_export.h"
 #include "ash/system/logout_button/logout_button_observer.h"
+#include "ash/system/logout_button/logout_confirmation_dialog_view.h"
 #include "ash/system/tray/tray_background_view.h"
 #include "ash/system/user/login_status.h"
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/time/time.h"
 #include "ui/views/controls/button/button.h"
 
 namespace views {
@@ -23,9 +27,9 @@ class StatusAreaWidget;
 
 // Adds a logout button to the launcher's status area if enabled by the
 // kShowLogoutButtonInTray pref.
-class LogoutButtonTray : public TrayBackgroundView,
-                         public LogoutButtonObserver,
-                         public views::ButtonListener {
+class ASH_EXPORT LogoutButtonTray : public TrayBackgroundView,
+                                    public LogoutButtonObserver,
+                                    public views::ButtonListener {
  public:
   explicit LogoutButtonTray(StatusAreaWidget* status_area_widget);
   virtual ~LogoutButtonTray();
@@ -39,6 +43,7 @@ class LogoutButtonTray : public TrayBackgroundView,
 
   // LogoutButtonObserver:
   virtual void OnShowLogoutButtonInTrayChanged(bool show) OVERRIDE;
+  virtual void OnLogoutDialogDurationChanged(base::TimeDelta duration) OVERRIDE;
 
   // views::ButtonListener:
   virtual void ButtonPressed(views::Button* sender,
@@ -46,12 +51,30 @@ class LogoutButtonTray : public TrayBackgroundView,
 
   void UpdateAfterLoginStatusChange(user::LoginStatus login_status);
 
+  // Nullify the pointer to confirmation dialog, this is expected to be called
+  // when the confirmation dialog is going to be destroyed.
+  // Note: the confirmation dialog is not owned by LogoutButtonTray.
+  void ReleaseConfirmationDialog();
+
+  void SetDelegateForTest(
+      scoped_ptr<LogoutConfirmationDialogView::Delegate> delegate);
+
  private:
+  friend class LogoutConfirmationDialogTest;
+
+  bool IsConfirmationDialogShowing() const;
+  void EnsureConfirmationDialogIsShowing();
+  void EnsureConfirmationDialogIsClosed();
+
   void UpdateVisibility();
 
   views::LabelButton* button_;  // Not owned.
   user::LoginStatus login_status_;
   bool show_logout_button_in_tray_;
+  base::TimeDelta dialog_duration_;
+
+  LogoutConfirmationDialogView* confirmation_dialog_;  // Not owned.
+  scoped_ptr<LogoutConfirmationDialogView::Delegate> confirmation_delegate_;
 
   DISALLOW_COPY_AND_ASSIGN(LogoutButtonTray);
 };