Remove the most obvious dead code from message center.

chrome/browser/ui/views/message_center/web_notification_tray.cc

Index: chrome/browser/ui/views/message_center/web_notification_tray.cc
diff --git a/chrome/browser/ui/views/message_center/web_notification_tray.cc b/chrome/browser/ui/views/message_center/web_notification_tray.cc
index d8ae5951ad8cf9cc5d604ef1a670b75ce78337e4..f8de34f6ce28ba44d19c62e3f433786ca750d96f 100644
--- a/chrome/browser/ui/views/message_center/web_notification_tray.cc
+++ b/chrome/browser/ui/views/message_center/web_notification_tray.cc
@@ -198,13 +198,6 @@ void WebNotificationTray::HideMessageCenter() {
   message_center_bubble_.reset();
 }
 
-void WebNotificationTray::UpdatePopups() {
-  // |popup_collection_| receives notification add/remove events and updates
-  // itself, so this method doesn't need to do anything.
-  // TODO(mukai): remove this method (currently this is used by
-  // non-rich-notifications in ChromeOS).
-};
-
 bool WebNotificationTray::ShowNotifierSettings() {
   if (message_center_bubble_) {
     static_cast<MessageCenterBubble*>(