Fixed all unused-variable Clang warnings on Windows.

cloud_print/common/win/install_utils.cc

 // Copyright 2013 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 "cloud_print/common/win/install_utils.h"
 
 #include <windows.h>
 
 #include "base/command_line.h"
 #include "base/file_version_info_win.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/path_service.h"
 #include "base/process/launch.h"
 #include "base/win/registry.h"
 #include "cloud_print/common/win/cloud_print_utils.h"
 
 namespace cloud_print {
 
 namespace {
 
 // Google Update related constants.
 const wchar_t kClientsKey[] = L"SOFTWARE\\Google\\Update\\Clients\\";
 const wchar_t kClientStateKey[] = L"SOFTWARE\\Google\\Update\\ClientState\\";
-const wchar_t* kUsageKey = L"dr";
 const wchar_t kVersionKey[] = L"pv";
 const wchar_t kNameKey[] = L"name";
 
 enum InstallerResult {
   INSTALLER_RESULT_FAILED_CUSTOM_ERROR = 1,
   INSTALLER_RESULT_FAILED_SYSTEM_ERROR = 3,
 };
 
 const wchar_t kRegValueInstallerResult[] = L"InstallerResult";
 const wchar_t kRegValueInstallerResultUIString[] = L"InstallerResultUIString";
@@ skipping 174 matching lines @@
 
 bool IsProgramsFilesParent(const base::FilePath& path) {
   base::FilePath program_files;
   if (!PathService::Get(base::DIR_PROGRAM_FILESX86, &program_files))
     return false;
   return program_files.IsParent(path);
 }
 
 }  // namespace cloud_print