Add countdown when session time is limited

ash/system/tray/test_system_tray_delegate.cc

Index: ash/system/tray/test_system_tray_delegate.cc
diff --git a/ash/system/tray/test_system_tray_delegate.cc b/ash/system/tray/test_system_tray_delegate.cc
index 87357340538c59d1acaf1488c767b37d0cbd750b..e2a2b1e9527b66d1efa767c622abf2ff6a7ea4f5 100644
--- a/ash/system/tray/test_system_tray_delegate.cc
+++ b/ash/system/tray/test_system_tray_delegate.cc
@@ -303,5 +303,13 @@ void TestSystemTrayDelegate::SetVolumeControlDelegate(
   volume_control_delegate_ = delegate.Pass();
 }
 
+bool TestSystemTrayDelegate::GetSessionLengthLimited() {
+  return false;
+}
+
+base::TimeDelta TestSystemTrayDelegate::GetRemainingSessionTime() {
+  return base::TimeDelta();
+}
+
 }  // namespace test
 }  // namespace ash