Replace more ObserverList with base::ObserverList.

content/browser/download/download_item_impl.h

 // 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.
 
 #ifndef CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_ITEM_IMPL_H_
 #define CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_ITEM_IMPL_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 475 matching lines @@
   // Start time for recording statistics.
   base::TimeTicks start_tick_;
 
   // The current state of this download.
   DownloadInternalState state_;
 
   // Current danger type for the download.
   DownloadDangerType danger_type_;
 
   // The views of this item in the download shelf and download contents.
-  ObserverList<Observer> observers_;
+  base::ObserverList<Observer> observers_;
 
   // Time the download was started.
   base::Time start_time_;
 
   // Time the download completed.
   base::Time end_time_;
 
   // Our delegate.
   DownloadItemImplDelegate* delegate_;
 
@@ skipping 44 matching lines @@
   const net::BoundNetLog bound_net_log_;
 
   base::WeakPtrFactory<DownloadItemImpl> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(DownloadItemImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_ITEM_IMPL_H_