Remove status icon if there are no more notifications.

chrome/browser/ui/views/message_center/web_notification_tray.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 "chrome/browser/ui/views/message_center/web_notification_tray.h"
 
 #include "base/i18n/number_formatting.h"
 #include "base/prefs/pref_service.h"
 #include "base/strings/string16.h"
 #include "base/strings/utf_string_conversions.h"
@@ skipping 258 matching lines @@
 
   base::string16 tool_tip;
   if (unread_notifications > 0) {
     base::string16 str_unread_count = base::FormatNumber(unread_notifications);
     tool_tip = l10n_util::GetStringFUTF16(IDS_MESSAGE_CENTER_TOOLTIP_UNREAD,
                                           str_unread_count);
   } else {
     tool_tip = l10n_util::GetStringUTF16(IDS_MESSAGE_CENTER_TOOLTIP);
   }
 
+  if (message_center()->GetVisibleNotifications().empty()) {
+    DestroyStatusIcon();
+    return;
+  }
+
   gfx::ImageSkia* icon_image = GetIcon(
       unread_notifications,
       message_center()->IsQuietMode());
 
   if (status_icon_) {
     status_icon_->SetImage(*icon_image);
     status_icon_->SetToolTip(tool_tip);
     return;
   }
 
@@ skipping 105 matching lines @@
   status_icon_menu_ = menu.get();
   status_icon->SetContextMenu(menu.Pass());
 }
 
 MessageCenterWidgetDelegate*
 WebNotificationTray::GetMessageCenterWidgetDelegateForTest() {
   return message_center_delegate_;
 }
 
 }  // namespace message_center