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

ash/system/tray/system_tray_notifier.cc

Index: ash/system/tray/system_tray_notifier.cc
diff --git a/ash/system/tray/system_tray_notifier.cc b/ash/system/tray/system_tray_notifier.cc
index e2035ad357feac1cf666d476d936a5477be47190..e0734bcd0676fa098c5f0ec518891d5dfdf3e1cf 100644
--- a/ash/system/tray/system_tray_notifier.cc
+++ b/ash/system/tray/system_tray_notifier.cc
@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 #include "ash/system/tray/system_tray_notifier.h"
+#include "base/time/time.h"
 
 #if defined(OS_CHROMEOS)
 #include "ash/system/chromeos/network/network_state_notifier.h"
@@ -232,6 +233,13 @@ void SystemTrayNotifier::NotifyShowLoginButtonChanged(bool show_login_button) {
                     OnShowLogoutButtonInTrayChanged(show_login_button));
 }
 
+void SystemTrayNotifier::NotifyLogoutDialogDurationChanged(int duration) {
+  base::TimeDelta duration_ = base::TimeDelta::FromMilliseconds(duration);

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

Nit 1: const
Nit 2: The _ at the end is used for member variables only, not for local
variables.

+  FOR_EACH_OBSERVER(LogoutButtonObserver,
+                    logout_button_observers_,
+                    OnLogoutDialogDurationChanged(duration_));
+}
+
 void SystemTrayNotifier::NotifyLocaleChanged(
     LocaleObserver::Delegate* delegate,
     const std::string& cur_locale,