Guard against more NULL pointers in WebstoreInstaller.

chrome/browser/extensions/webstore_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_EXTENSIONS_WEBSTORE_INSTALLER_H_
 #define CHROME_BROWSER_EXTENSIONS_WEBSTORE_INSTALLER_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 140 matching lines @@
   // this managed its installation. This also removes the associated
   // PendingInstall.
   void ReportSuccess();
 
   content::NotificationRegistrar registrar_;
   Profile* profile_;
   Delegate* delegate_;
   content::NavigationController* controller_;
   std::string id_;
   // The DownloadItem is owned by the DownloadManager and is valid from when
-  // OnDownloadStarted is called (with no error) until the DownloadItem
-  // transitions to state REMOVING.
+  // OnDownloadStarted is called (with no error) until OnDownloadDestroyed().
   content::DownloadItem* download_item_;
-  int flags_;
   scoped_ptr<Approval> approval_;
   GURL download_url_;
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_WEBSTORE_INSTALLER_H_