Show no-notification message in the bottom label of message center

ui/message_center/views/message_center_view_unittest.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/message_center/views/message_center_view.h"
 
 #include <map>
 #include <memory>
 #include <utility>
 
@@ skipping 180 matching lines @@
       base::UTF8ToUTF16("display source"), GURL(),
       NotifierId(NotifierId::APPLICATION, "extension_id"),
       message_center::RichNotificationData(), NULL);
 
   // ...and a list for it.
   notifications_.insert(notification1);
   notifications_.insert(notification2);
   message_center_->SetVisibleNotifications(notifications_);
 
   // Then create a new MessageCenterView with that single notification.
-  base::string16 title;
   message_center_view_.reset(new MessageCenterView(
-      message_center_.get(), NULL, 100, false, /*top_down =*/false, title));
+      message_center_.get(), NULL, 100, false, /*top_down =*/false));
   GetMessageListView()->quit_message_loop_after_animation_for_test_ = true;
   GetMessageCenterView()->SetBounds(0, 0, 380, 600);
   message_center_view_->SetNotifications(notifications_);
 
   // Wait until the animation finishes if available.
   if (GetAnimator()->IsAnimating())
     base::MessageLoop::current()->Run();
 }
 
 void MessageCenterViewTest::TearDown() {
@@ skipping 380 matching lines @@
   AddNotification(
       std::unique_ptr<Notification>(new Notification(pinned_notification)));
 
   // There should be 1 pinned notification.
   EXPECT_EQ(1u, GetMessageCenter()->GetVisibleNotifications().size());
   EXPECT_FALSE(close_button->enabled());
 #endif  // defined(OS_CHROMEOS)
 }
 
 }  // namespace message_center