Fixit: Remove bunch of coverity warnings from chrome/installer/*.

chrome/installer/util/delete_tree_work_item.h

-// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
+// Copyright (c) 2009 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_INSTALLER_UTIL_DELETE_TREE_WORK_ITEM_H__
-#define CHROME_INSTALLER_UTIL_DELETE_TREE_WORK_ITEM_H__
+#ifndef CHROME_INSTALLER_UTIL_DELETE_TREE_WORK_ITEM_H_
+#define CHROME_INSTALLER_UTIL_DELETE_TREE_WORK_ITEM_H_
 
 #include <string>
 #include <windows.h>
 #include "chrome/installer/util/work_item.h"
 
 // A WorkItem subclass that recursively deletes a file system hierarchy at the
 // given root path. The file system hierarchy could be a single file, or a
 // directory.
 // The file system hierarchy to be deleted can have a key file. If the key file
 // is specified, deletion will be performed only if the key file is not in use.
 class DeleteTreeWorkItem : public WorkItem {
  public:
   virtual ~DeleteTreeWorkItem();
 
   virtual bool Do();
 
   virtual void Rollback();
 
  private:
   friend class WorkItem;
 
   // Get a backup path that can keep root_path_ or key_path_
-  bool GetBackupPath(std::wstring for_path, std::wstring* backup_path);
+  bool GetBackupPath(const std::wstring& for_path, std::wstring* backup_path);
 
-  DeleteTreeWorkItem(std::wstring root_path, std::wstring key_path);
+  DeleteTreeWorkItem(const std::wstring& root_path,
+                     const std::wstring& key_path);
 
   // Root path to delete.
   std::wstring root_path_;
 
   // Path to the key file. If the key file is specified, deletion will be
   // performed only if the key file is not in use.
   std::wstring key_path_;
 
   // The full path in temporary directory that the original root_path_ has
   // been moved to.
   std::wstring backup_path_;
 
   // The full path in temporary directory that the original key_path_ has
   // been moved to.
   std::wstring key_backup_path_;
 };
 
-#endif  // CHROME_INSTALLER_UTIL_DELETE_TREE_WORK_ITEM_H__
+#endif  // CHROME_INSTALLER_UTIL_DELETE_TREE_WORK_ITEM_H_