Do not activate TrayBubbleView by default

ui/message_center/views/message_bubble_base.cc

 // Copyright (c) 2012 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_bubble_base.h"
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/single_thread_task_runner.h"
 #include "base/threading/thread_task_runner_handle.h"
@@ skipping 13 matching lines @@
                                      MessageCenterTray* tray)
     : message_center_(message_center),
       tray_(tray),
       bubble_view_(NULL),
       max_height_(kMessageBubbleBaseDefaultMaxHeight),
       weak_ptr_factory_(this) {
 }
 
 MessageBubbleBase::~MessageBubbleBase() {
   if (bubble_view_)
-    bubble_view_->reset_delegate();
+    bubble_view_->ResetDelegate();
 }
 
 void MessageBubbleBase::BubbleViewDestroyed() {
   bubble_view_ = NULL;
   OnBubbleViewDestroyed();
 }
 
 void MessageBubbleBase::ScheduleUpdate() {
   weak_ptr_factory_.InvalidateWeakPtrs();  // Cancel any pending update.
   base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
@@ skipping 12 matching lines @@
     height = kMessageBubbleBaseDefaultMaxHeight;
   if (height == max_height_)
     return;
 
   max_height_ = height;
   if (bubble_view_)
     bubble_view_->SetMaxHeight(max_height_);
 }
 
 }  // namespace message_center