Remove unused reference to DownloadManager in PluginInstaller

chrome/browser/plugins/plugin_installer.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 CHROME_BROWSER_PLUGINS_PLUGIN_INSTALLER_H_
 #define CHROME_BROWSER_PLUGINS_PLUGIN_INSTALLER_H_
 
 #include "base/observer_list.h"
 #include "base/string16.h"
 #include "base/version.h"
@@ skipping 37 matching lines @@
   // Opens the download URL in a new tab.
   void OpenDownloadURL(const GURL& plugin_url,
                        content::WebContents* web_contents);
 
   // Starts downloading the download URL and opens the downloaded file
   // when finished.
   void StartInstalling(const GURL& plugin_url,
                        content::WebContents* web_contents);
 
  private:
-  void DownloadStarted(scoped_refptr<content::DownloadManager> dlm,
-                       content::DownloadItem* item,
-                       net::Error error);
+  void DownloadStarted(content::DownloadItem* item, net::Error error);
   void DownloadError(const std::string& msg);
   void DownloadCancelled();
 
   InstallerState state_;
   ObserverList<PluginInstallerObserver> observers_;
   ObserverList<WeakPluginInstallerObserver> weak_observers_;
 
   DISALLOW_COPY_AND_ASSIGN(PluginInstaller);
 };
 
 #endif  // CHROME_BROWSER_PLUGINS_PLUGIN_INSTALLER_H_