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

chrome/installer/util/copy_tree_work_item.cc

-// 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.
 
 #include "chrome/installer/util/copy_tree_work_item.h"
 
 #include <shlwapi.h>
 #include "base/file_util.h"
 #include "chrome/installer/util/logging_installer.h"
 
 CopyTreeWorkItem::~CopyTreeWorkItem() {
   if (file_util::PathExists(backup_path_)) {
     file_util::Delete(backup_path_, true);
   }
 }
 
-CopyTreeWorkItem::CopyTreeWorkItem(std::wstring source_path,
-                                   std::wstring dest_path,
-                                   std::wstring temp_dir,
+CopyTreeWorkItem::CopyTreeWorkItem(const std::wstring& source_path,
+                                   const std::wstring& dest_path,
+                                   const std::wstring& temp_dir,
                                    CopyOverWriteOption overwrite_option,
-                                   std::wstring alternative_path)
+                                   const std::wstring& alternative_path)
     : source_path_(source_path),
       dest_path_(dest_path),
       temp_dir_(temp_dir),
       overwrite_option_(overwrite_option),
       alternative_path_(alternative_path),
       copied_to_dest_path_(false),
       moved_to_backup_(false),
       copied_to_alternate_path_(false) {
 }
 
@@ skipping 77 matching lines @@
   }
   if (moved_to_backup_ && !file_util::Move(backup_path_, dest_path_)) {
     LOG(ERROR) << "failed move " << backup_path_ << " to " << dest_path_;
   }
   if (copied_to_alternate_path_ &&
       !file_util::Delete(alternative_path_, true)) {
     LOG(ERROR) << "Can not delete " << alternative_path_;
   }
 }
 
-bool CopyTreeWorkItem::IsFileInUse(std::wstring path) {
+bool CopyTreeWorkItem::IsFileInUse(const std::wstring& path) {
   if (!file_util::PathExists(path))
     return false;
 
   HANDLE handle = ::CreateFile(path.c_str(), FILE_ALL_ACCESS,
                                NULL, NULL, OPEN_EXISTING, NULL, NULL);
   if (handle  == INVALID_HANDLE_VALUE)
     return true;
 
   CloseHandle(handle);
   return false;
 }
 
 bool CopyTreeWorkItem::GetBackupPath() {
   std::wstring file_name = file_util::GetFilenameFromPath(dest_path_);
   backup_path_.assign(temp_dir_);
   file_util::AppendToPath(&backup_path_, file_name);
 
   if (file_util::PathExists(backup_path_)) {
     // Ideally we should not fail immediately. Instead we could try some
     // random paths under temp_dir_ until we reach certain limit.
     // For now our caller always provides a good temporary directory so
     // we don't bother.
     LOG(ERROR) << "backup path " << backup_path_ << " already exists";
     return false;
   }
 
   return true;
 }