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

chrome/installer/util/copy_tree_work_item_unittest.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 <windows.h>
 
 #include <fstream>
 #include <iostream>
 
 #include "base/base_paths.h"
 #include "base/file_util.h"
@@ skipping 42 matching lines @@
   // Simple function to dump some text into a new file.
   void CreateTextFile(const std::wstring& filename,
                       const std::wstring& contents) {
     std::ofstream file;
     file.open(filename.c_str());
     ASSERT_TRUE(file.is_open());
     file << contents;
     file.close();
   }
 
-  bool IsFileInUse(std::wstring path) {
+  bool 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;
@@ skipping 612 matching lines @@
   LOG(INFO) << "compare " << file_name_from_1 << " and " << file_name_to_1;
   EXPECT_TRUE(file_util::ContentsEqual(file_name_from_1, file_name_to_1));
 
   std::wstring file_name_to_2(dir_name_to);
   file_util::AppendToPath(&file_name_to_2, L"2");
   file_util::AppendToPath(&file_name_to_2, L"File_2.txt");
   EXPECT_TRUE(file_util::PathExists(file_name_to_2));
   LOG(INFO) << "compare " << file_name_from_2 << " and " << file_name_to_2;
   EXPECT_TRUE(file_util::ContentsEqual(file_name_from_2, file_name_to_2));
 }