clang/win: Let some chromium_code targets build with -Wextra.

chrome/installer/util/installer_state.cc

 // 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.
 
 #include "chrome/installer/util/installer_state.h"
 
 #include <algorithm>
 #include <functional>
 #include <utility>
 
@@ skipping 503 matching lines @@
 
 void InstallerState::GetExistingExeVersions(
     std::set<std::string>* existing_versions) const {
 
   static const wchar_t* const kChromeFilenames[] = {
     installer::kChromeExe,
     installer::kChromeNewExe,
     installer::kChromeOldExe,
   };
 
-  for (int i = 0; i < arraysize(kChromeFilenames); ++i) {
+  for (size_t i = 0; i < arraysize(kChromeFilenames); ++i) {
     base::FilePath chrome_exe(target_path().Append(kChromeFilenames[i]));
     scoped_ptr<FileVersionInfo> file_version_info(
         FileVersionInfo::CreateFileVersionInfo(chrome_exe));
     if (file_version_info) {
       base::string16 version_string = file_version_info->file_version();
       if (!version_string.empty() && base::IsStringASCII(version_string))
         existing_versions->insert(base::UTF16ToASCII(version_string));
     }
   }
 }
@@ skipping 153 matching lines @@
   }
   if (!install_list->Do())
     LOG(ERROR) << "Failed to record installer error information in registry.";
 }
 
 bool InstallerState::RequiresActiveSetup() const {
   return system_install() && FindProduct(BrowserDistribution::CHROME_BROWSER);
 }
 
 }  // namespace installer